Chapter Text
“Don’t you think the Cave is a little…unsafe?” a voice called from behind.
Bruce wondered where that sentiment was coming from. He swivelled around in his chair, coming face-to-face with his second-youngest child.
“It’s been this way since Dick was a child,” Bruce said, unimpressed. “And last I checked, Damian was much less likely to try and swing from the stalactites than your eight-year-old older brother.”
“Dick tried to swing from the stalactites?” Duke asked, a thread of bemused admiration in his tone.
“Didn’t he ever,” Bruce muttered, turning back to his work.
Duke finally made it to the Batcomputer, forcibly rotating the chair back around. Duke was wearing the bottom half of the Signal undersuit, the all-black underarmour tight against his skin. A loose long-sleeved shirt covered his chest. It got chilly in the Cave in winter.
Bruce was dressed similarly, wearing just the Batsuit’s underarmour, though he wore one of Clark’s oversized navy sweaters. Clark claimed they were stolen. Bruce preferred the term liberated.
“See, now I have to hear this,” Duke said, hopping up to sit on the desk the Batcomputer rested on. Bruce shot him a mild glare, but obligingly moved his mousepad out of the way to make more room for him.
Bruce began obligingly, “when Dick was younger—”
“Holy black eye, Batman!” Duke interrupted, leaning closer to Bruce. Bruce reached a hand out to steady him, bemused. “What happened to your face?”
“Hm?”
“You should be on concussion watch, B, if someone managed to bruise you through your cowl.”
Oh.
“My cowl was off,” Bruce dismissed. Duke’s brows furrowed.
“Forgive me if I’m wrong,” Duke started dryly. “But I feel like it’s against Bat-protocol to take your cowl off mid-fight.”
“It is,” Bruce grunted. “Hood and I had a— hn— incident.”
Thankfully, Duke didn’t press.
“Actually, I wanted to ask for your help on a case,” Duke said, commandeering Bruce’s mouse. Bruce let out a long breath in exasperation as Duke pulled up a file from an ongoing case, covering the windows he already had open.
“You do realise I was already working on something,” Bruce objected mildly, making no move to regain control of the computer.
“If you really minded, you would have already stopped me,” Duke rebutted, ignoring him completely.
Bruce didn’t deny it. It was true, after all.
Duke clicked on a video file, loading surveillance footage from a CCTV camera. “Burnley,” Duke elaborated. “Outside of that one convenience story with the dinky open sign. You know the one.”
Bruce did, in fact, know the one.
Duke clicked play, letting the video speak for itself.
Immediately, Bruce’s stomach shot up into his chest.
Signal was fighting against Zsasz.
Signal hadn’t yet been cleared to grapple with the likes of trained killers like Zsasz, but it wasn’t as if Zsasz knew or cared about the tiny files and notes that littered Bruce’s training profiles of his children.
The recording glitched in and out, responding to Duke’s instinctive use of his powers as he fought. Still, despite Duke’s metahuman advantage, it was clear he was struggling to keep up with Zsasz’s flashing knife and quicksilver blows.
It was also confirmation of what Bruce had previously suspected: there was a leak in Arkham.
Arkham’s records showed that Zsasz was still in custody. He’d bet anything that the footage in Zsasz’s cell was looped over several hours— the footage he hadn't been allowed to see because of supposed "new changes" in the asylum's HIPAA policy.
Bruce couldn’t swallow around the lump in his throat as he continued to watch the fight.
The video-Duke eventually began to tire, but Zsasz, if anything, only grew more invigorated. He landed several slashes against Duke’s armoured forearms, which were raised to protect his face.
“Watch out,” Duke warned, just before the footage burst into blinding light.
When the light subsided, Duke was gone and Zsasz was shielding his eyes ineffectually with his arms. Zsasz blinked ineffectually several times, letting out a furious growl when he realised Signal’s absence.
“Impressive save,” Bruce said, blinking the spots out of his own vision. “Did you grapple onto the roof? I couldn’t see what happened.”
“No,” Duke paused, a tinge of panic bleeding through his next words. “I didn’t mean to do it. The light, or what happened after.” Bruce’s brows furrowed.
“…after?”
“Just— just watch.”
Duke began to glow, light emitted softly from his every pore. Bruce shielded his eyes, but he didn’t really seem to need to. Duke didn’t grow as bright as he did in the video.
The light faded quickly, and Bruce lowered his hand. Duke was gone. Bruce lifted a manicured eyebrow in slight surprise.
“Well, that’s new,” he said wryly, inspecting the slight shimmer in the air where Duke had been. It seemed concentrated around his costume— the areas where his skin and hair were bare merged effortlessly into the background of the Cave.
“B, I can’t control it.” Duke’s disembodied voice floated out. “Ever since then, whenever I’m nervous, or sometimes even just excited, there’s a light-show, and then poof!” Duke’s voice rose higher and faster in his anxiety. “What if it happens on patrol? With my friends? At school? Ohmygodwhatifithappensat—”
“Shh,” Bruce soothed, eyes trained on that shimmer. “We’ll figure this out.” Bruce’s voice was calm and reassuring, even as his thoughts whirled, racing through every test he would need to run and searching for anything that could have triggered this change in Duke’s powers.
He stood, holding his arms out. A body ducked into his arms— solid, if invisible. Bruce crossed another few possibilities off of the list whipping through his mind. Duke’s tremors began to relax, his muscles loosening.
Bruce held Duke for a long moment, resting his chin in Duke’s curls and inhaling. His hair smelled like shea butter and coconut, likely from his curl cream.
Duke slowly faded into sight, starting with his suit. Colour bled from the edges of his undersuit to his more distal skin, like a paper towel dipped in dye.
“Let’s run some tests,” Bruce said gently, guiding Duke to the lab area in the cave. Bruce ignored the slight twinge in his ankle as the Cave floor slanted down towards the lab.
He sat Duke down on one of the examination tables, neatly preparing an IV needle and six vials to collect blood in. Duke tugged his shirt sleeve up, the loose fabric billowing over the elastic wristband where it sat above his elbow. Duke had already wrapped his fists and forearms underneath his suit, long white strips protecting his knuckles and ulnas.
Bruce wrapped a tourniquet around Duke’s upper arm— yellow, of course— and inserted the needle neatly. The tubing filled with dark venous blood, flowing upwards. He extracted the spike, leaving only the plastic tubing behind.
Duke watched morbidly as his blood filled the vials Bruce held carefully to the end of the tubing. “Six whole vials?” he complained, only half-joking. “Are you running tests, or feeding a vampire?”
“Some of it is for the bats,” Bruce said mildly. “They like it as a treat.” Duke looked up at his face, startled.
“No shit?”
Bruce’s face betrayed him, his lips twitching the slightest amount. Duke’s expression shifted, and he turned his head away to hide his pout.
“God, you’re such an ass.”
Bruce laughed aloud, removing the IV and bandaging the small puncture wound. He set the vials to the side, unwrapping a cotton swab and turning Duke’s jaw back over.
Duke opened his mouth long-sufferingly, wincing as Bruce swabbed at his cheek rather roughly, to get a sample of his buccal epithelial cells.
“‘Eawwy, Wooce? ‘at ‘huwts! ‘on’t oo aweady ‘ave a EeNA ‘ample?” Duke complained, mouth held open. Bruce ignored him, swabbing until he was certain he had a good sample.
Duke closed his mouth sullenly as Bruce withdrew the swab. He would need to smear that onto a microscope slide and dye it, but that would all come later. He needed to start sequencing the DNA first, so that he would have a better idea of which tests to rule out.
But Bruce had to deal with a larger issue first. Duke still wasn’t fully trained. Bruce had let him out into the field because he was pretty sure Duke would burn the Manor down, Batcave and all, if Bruce benched him now, after all of his experience with the Robin gang. And while that was generally enough for the majority of Gotham’s thugs, it wasn’t enough for adversaries like Zsasz or Deathstroke.
“On the mats,” Bruce ordered. “Warm up.” Duke groaned, sliding off the exam table. Bruce took a moment to store five of the six bottles of blood safely. He would need to analyse one for magic, another for chemical contamination…but for now, he would start with the most likely culprit: DNA. One the regular sequencing was done, he would run an epigenetic sequence with a hybridization array
He mixed ammonium chloride into the sample as Duke continued to warm up on the mats. He was fresh and ready to patrol; Bruce had just gotten back from a long night on the streets. It was one of those rare times when their schedules overlapped enough that they could take a moment together in that ephemeral space in-between vigilante and celebrity. Plus, it would do Duke good to warm up a little before patrol.
He set a five-minute timer to start the centrifuge, before making his way to the mats. He was already mostly warmed-up, though his sweat had long cooled and dried tacky on the small of his back. He would have showered, but Clark was coming over in a little bit, and it would make more sense to shower after.
Duke was waiting for him in a loose ready stance, feet bare against the mat. Bruce toed off his fluffy Nightwing-blue socks— Dick had gotten them for him as a gag gift, but Bruce wore them unironically— and stepped onto the mats.
Duke’s stance firmed, and they began to circle each other, like sharks in open water.
Bruce rarely struck first, when training with his kids. Part of the reason was so that they would learn when to strike, noticing and capitalising upon the slightest drop in an opponent’s guard. Part of it was to train them out of complacency, in preparation for those rare times he did strike first.
Bruce let his arm fly forwards, lightning fast.
Duke moved back fluidly enough, only mildly startled by Bruce’s quicksilver jab. He countered with a kick to the side, which Bruce dodged easily. They traded blows, Duke maintaining pace with him. This was mostly a testing round, to feel out any mistakes or lapses in Duke’s guard, so Bruce let Duke push him back in favour of analysing Duke’s weight distribution and blow patterns.
Bruce landed a hit against Duke’s cheekbone, purposefully gentled so as to not cause pain. Duke grumbled in acknowledgement, even as he shot a hand out at Bruce’s midsection. Bruce deflected the blow with his forearm, ducking it down in defence of his abdomen.
Bruce’s blows were mostly defensive. Bruce wasn’t here to show off his own fighting skills; he was here to teach Duke. Still, he picked up his game when Duke did, aiming a forceful feint towards Duke’s forehead before redirecting it to the side to tap under his jaw.
Duke ducked down, aiming a tap against Bruce's spleen. Bruce blocked the strike, jabbing at Duke's shoulder. Duke avoided the blow, shifting his weight up— Duke dropped to the mat.
He swept his leg out, taking Bruce out at the ankle. His ankle slid across the mat, knocked aside by the force of Duke's kick. Bruce's strained ankle couldn’t handle his sudden shift in weight, and he hit the mat with an oompfh, the impact reverberating through his body.
“Sorry!” Duke called, but Bruce could tell he was unrepentant in the slightest. A single glance at Duke’s satisfied expression showed his choice of move hadn’t been random.
“Good catch,” Bruce said, rolling out his ankle. A series of clicks followed the motion. He was surprised Duke had caught it; he hadn’t remembered telling him about the injury.
“You were favouring your left side when we walked to the lab,” Duke explained. “You stopped when we started sparring, but I remembered.”
Bruce’s lips twitched. So, not a mistake replicable in the field. Bruce would only ever let himself show something so obvious as favouring a side at home, surrounded by family.
“Hn.”
“The ankle have anything to do with your black eye?” Duke asked cheekily. “Or are you just getting old?”
“Alright, wise-ass,” Bruce said, laughing. He stood and grabbed two blunted knives from the practice armoury. “No more Mr. Nice-Batman.”
“That was supposed to be nice? I couldn't even tell,” Duke snarked. “Maybe you are getting old…”
“Ha, ha. Let’s see what you say in two minutes, once you’re looking up at me from the mat.”
Bruce let his memory of Zsasz’s fighting style flow down his limbs, mirroring Zsasz’s body language and posture. Duke observed him warily.
“You have to know that’s creepy, Bruce,” Duke said, wrinkling his nose at him. “You’re even smiling like him.”
Bruce let his grin stretch wider, just as Zsasz’s would, and with no other telegraphing, struck. Duke countered his sudden blow with a muffled curse, locking his forearm against Bruce’s to push him away. Bruce sped up the frequency of his slashes, escalating the stakes. Duke defended himself adequately, much as he had in the video.
Still. Bruce could tell it wasn’t enough. He stabbed forward, the tip of the knife brushing just under Duke’s sternum.
“Dead.”
Duke growled, spinning around to aim a roundhouse kick at Bruce. Bruce-Zsasz dodged, redirecting it to land into the air. Duke overbalanced, tipping forward. He corrected himself quickly, but Bruce had already managed to brush the knife across his jugular.
“Dead,” he said again. “Focus more on your footwork. Grab the hilt of the knife or otherwise force it out of my grip. Aim for the throat and eyes.”
Bruce regretted it even as he said it. His throat was still sore from the other day, but it still was a good tip. Bruce would just have to be extra on-guard to avoid a strike there. The undersuit covered his neck for good reason; he didn’t want anyone seeing the damage Jason’s attack had done. It would only cause unnecessary drama and guilt.
Duke redoubled his efforts against Bruce, hands striking up to Bruce’s neck and eyes. Bruce ducked down, slashing up in a long arc. The tip of the knife grazed the weak points in the armour, and Bruce pressed just a little harder at those spots, to further illustrate his point.
“Dead.” Bruce jabbed Duke lightly in the side for good measure, the cool metal pressing against the vulnerable flesh of his abdomen.
Duke’s eyes flashed. The shadows around his feet disappeared. Bruce attacked then in a flurry of motion, before Duke could process his vision and see Bruce’s future moves. But instead of retaliating with the kind of targeted attacks Bruce would have expected, Duke moved only just enough to not get hit. It was almost as if he was focusing on something…
Duke disappeared into thin air.
Bruce stilled immediately. They would train against Duke’s invisibility eventually-- it would be good practice-- but not before they understood his powers, and especially not with knives in hand. The knives were tugged gently out of his hands, and he let them go, unresisting.
A cold finger poked his neck.
“Dead,” Duke said cheerily.
Bruce swatted at Duke lightly. Duke’s laughter hung in the air, bright and contagious. Bruce let himself smile, his lips turning up at the corners ever-so-slightly.
Which reminded him.
“What changed?” Bruce asked, as he moved back over to the lab. He inserted the vial into a centrifuge. He filled a counterweight with water before turning the centrifuge on. “You couldn’t control it before.”
“I don’t think I can necessarily control it yet, B,” Duke admitted, voice floating through the Cave. Bruce tracked it as the voice moved to set the knives down. “I just let myself get excited at the thought of tricking you, and then, well.”
“Hn.”
Duke neared him, soft footsteps echoing through the Cave. Bruce knew Duke was purposefully moving loud enough to be heard, and Bruce felt his chest warm at the thoughtful gesture.
“Um,” said Duke. “Oops.”
Bruce jerked his head around. Duke was once again visible, though the edges of his silhouette were blurry and faded. Red soaked through the sleeves of his grey shirt, the iron tang of blood bursting in the air.
Duke was quickly whirled to the med bay, the sleeves on his shirt tugged down. The wounds were long and jagged, the skin sticking to the bandages as Bruce carefully peeled them off. Zsasz's knives must have cut through the armour. Bruce made a mental note to inspect and upgrade Signal's suit.
Bruce's face was grim as he inspected the wounds, which had so far avoided infection, but definitely would not close on their own. Duke shouldn't have been training with this injury, especially since he had been using his unbraced forearms to block Bruce's strikes.
"I didn't think I needed stitches," Duke said, into Bruce's judgemental silence.
Despite himself, Bruce softened. Stitches were a complicated procedure with Duke.
His meta biology rendered most local anaesthetics useless, and Duke was allergic to the anaesthetic they used with most metas. The one Clark used was tuned carefully to Kryptonian DNA, and would be at best useless— at worst, it would be actively harmful. They had yet to find a good replacement.
"You do," Bruce said gently, pressing a hand against Duke's shoulder. He felt the slight tremor that went through Duke at his answer. "Will you let me do them?"
To add to Duke's anxiety, he didn't like needles. They reminded him of his parents, hooked up to dozens of tubes and kept in medicated sleep. Bruce didn't blame him; he still couldn't look at pearls.
There was a long pause, Duke visibly warring with himself.
While Duke deliberated, Bruce washed his hands to his elbow, the rushing water covering some of the awful quiet.
"…okay." Duke's voice was small when he finally agreed.
"I didn't finish telling you that story," Bruce said, voice purposefully light as he dried his hands.
"Which story?" Duke asked haltingly, eyes locked onto the plastic-wrapped hooked needle Bruce was removing from a drawer.
Deftly, Bruce snapped on a pair of gloves as he pressed the non-emergency call button with his elbow.
"The one about the chandeliers," Bruce said, preparing the suture material. A pair of sterile clamps and forceps were laid out beside the suture. "Dick was an absolute menace as a child. I had to reinforce every chandelier in the manor to make sure it would hold up under his weight."
Duke smiled despite himself, even as Bruce swabbed his forearms gently with an alcohol wipe. Duke hissed slightly as the wipe went over his wounds, but Bruce rubbed lightly at his shoulder with the back of two knuckles to try and soothe him.
Bruce's eyes caught on Duke's arm. As Duke's panic rose, his arm became more and more…transparent.
"We can take another minute, if you'd like. We're in no rush," Bruce said, shifting his gaze to Duke's face.
"No, you're tired," Duke disagreed. He hadn't seemed to notice his spreading invisibility. "You need to get to bed. I'm fine."
"Not that tired, kiddo," Bruce corrected, voice soft. "Tim is on his way down anyways. I'll have to re-swab your arms, but we can wait for him."
"Can— can we wait, then?"
"Of course."
"How has school been?" Bruce asked, somewhat awkwardly. Duke looked at him askance, recognizing the diversion tactic for what it was.
Sighing, Duke indulged him.
"—and they literally have not answered me in the group chat. It's due in two days. So I guess I'm doing the entire assignment myself, which, by the way, is a rap. About calculus."
"Is that for Mrs. Roberts?" Tim's amused voice floated down from the top of the staircase. "You poor thing." The staircase clanked noisily as Tim took the stairs two at a time, slamming the soles of his shoes into the metal. "She was the worst— always getting upset when I fell asleep in class. The number of times I had to hack into the school mainframe just to intercept her emails to my parents…" Tim's eyes darted to Bruce, and he back-tracked rapidly. "…not that I fell asleep in class. Um. Often."
"Tim." Bruce's tone was mild.
Tim blinked, turning towards Duke. His lips parted into a moue of understanding. His eyes flashed, rapidly calculating the scene in front of him. His expression eased even as the corners around his eyes tightened.
"Oh, that looks gnarly, Duke."
"I know." Duke sounded miserable.
"Need stitches?" Tim asked sympathetically, hopping up onto the cot beside Duke.
"Mhm. Courtesy of Zsasz."
Bruce watched them converse with a slight smile. Tim had really begun to grow into his older brother role, even though him and Duke weren't too far apart in age. Things had been tense for a long while, after his stint in the time stream. Bruce couldn't help but take this new tendency of Tim as a good sign.
"You ready, Duke?" Bruce asked. The lightness that had settled over the Medbay evaporated like mist, leaving behind a heavy feeling of foreboding.
Duke nodded, a minuscule motion of his head.
"Need a verbal answer, kiddo."
"…yeah."
Bruce picked up the suture and his sterile forceps and began.
Every tiny flinch and startle was like a lance to the heart. Tim kept up a steady commentary on trivial things, his thigh pressed against Duke's as a thin substitute for not really being able to hold Duke's hand.
Duke's teeth were gritted together, his lips pressed into a thin line. His eyes were squeezed shut, breathing carefully counted and measured. Still, his body was turned ever-so-slightly towards Tim, like a sunflower seeking light.
Bruce bandaged Duke's left forearm first, guiding it down to Duke's lap. Duke found Tim's hand instinctively, wrapping tightly around it. Tim suppressed a wince as Bruce continued suturing Duke's right arm.
Duke's breath hitched halfway through, and Bruce looked up sharply. Duke's eyes were wet and wide, locked onto the glint of the needle in Bruce's hand. Bruce's heart sunk.
Tim had noticed it too, lifting his free hand to gently turn Duke's head away from Bruce. Keep going, he mouthed at Bruce. Bruce took a steadying breath and pressed on, the needle sliding smoothly through Duke's skin.
"—just look at me," Bruce heard Tim say, almost as if through a haze, as he finished the last line of stitches. He wrapped Duke's arm, lowering it down to the cot.
"Good job, Duke," Bruce said, rubbing his hand in careful circles on Duke's back. "You did so well." The praise was stilted, but genuine.
Duke didn't answer verbally, but he pressed his forehead forward into Bruce's chest. Bruce moved one hand up around the back of Duke's neck, holding him in a cautious embrace. Tim snickered quietly at the expression on Bruce's face, snapping a quick photo before Bruce could react.
"I was just telling Duke about some of Dick's, ah, misadventures as Robin," Bruce redirected, before Tim could send that photo to the group chat. "I assume you have some photos laying about…?"
"Oh, do I ever!" Tim said gleefully, rubbing his hands together. "Hold on a sec."
Tim darted to his locker to retrieve the photos. It was only then that Bruce noticed what Tim was wearing.
"I like your shirt, Tim," Bruce commented lightly, suppressing a laugh. Duke's eyes widened, recognising the black-on-red. Tim flushed red, rummaging louder through his locker as if to avoid their sudden scrutiny.
Tim was in shorts and an oversized Superboy shirt. Innocuous enough, on its own. But the shirt was backwards, clearly put on in a hurry. The shorts slung low on Tim's hips, a size too large.
"At least do it in your own apartment," Duke teased. "Do both of you even fit on that twin mattres—"
"Shut up," Tim hissed, hiding his face behind his hands in an attempt to conceal his growing embarrassment. "Do you or do you not want to hear about Dick's stupid stunts as Robin? Because I can leave, and not tell you. That's a thing I can do."
"Leave where, exactly?" Duke asked, grinning cheekily. Duke ducked to avoid the incoming Batarang, laughing aloud. "Fine, fine. Sorry. Tell me about Dick. Better yet, do you have anything on Jason?"
"Hmph. Apology accepted." Tim extracted a small metal box from the bottom of his locker, padlocked shut. "And of course I do— what kind of a brother do you take me for? Now gather round as I explain lore heretofore unheard…"
Bruce's phone buzzed in his pocket.
You coming upstairs? read a text. Clark, Bruce realised, with a pang of fondness in his chest.
Just five more minutes, Bruce texted back, already setting his phone down to enjoy this rare moment with his sons.