The party first meet Viatrix shortly after she's run away from home and left her cult is in an uproar, sending agents both mortal and fiendish combing across the countryside searching for her, causing all kinds of havoc in the process. It's very likely that whatever settlement/caravan the party are taking shelter with will be beset by imps, hellhounds, and hooded figures who attack innocents at night while asking pressing questions.

Eight years pass, Damian and Danny are 17. Damian has been living with Bruce since he was 10 and still does not remember he has a twin. Talia still does not remember that she had two sons. 

Dante, now Danny,  still has no clear memories from before he was found by the Fentons. Even the accident with the portal did not bring back those memories.  By the time we start, he has already come out to his parents about being Phantom (in admittedly the most traumatizing way for the Fenton parents as possible-He, Tucker, and Sam sat them down and showed them the full raw security tapes of the accident before telling them anything. Jack and Maddie may be oblivious and obsessive but they are very intelligent. They realized almost immediately what it meant that their portal opened with Danny inside, even before he was spit out a blackened corpse who healed into Phantom). 

This is a good Fenton Parents, who not only took the half ghost realization well but also immediately became a bit obsessed with not only lab safety, as one of their inventions had killed one of their children, but also with understanding ghost culture. They also immediately started manufacturing weapons for ghosts to use against the GIW(The Fentons are 100%, ride or die, enthusiastic at all times and in this one the moment they realize that there were people hurting Danny…they were ready to rip the GIW apart molecule by molecule).  Phantom has also connected with the Justice League, joined the Justice League Dark, who were able to get the Anti Ecto Acts reversed. The Justice League as a whole knows that Phantom is a half ghost, half human King of the Infinite Realms whose civilian name is Danny Fenton but Batman, nor any of his kids, has not had the opportunity to meet Danny out of uniform, as it were.  Batman and Red Hood know and Trust Phantom, as he has also helped with the Pit Rage (The Lazarus Pits are corrupted Ectoplasm for the win).

Which brings us to our start. 

It’s a pretty basic premise. A Cult (14 people present) decides to summon the Ghost King for power.  When Danny was first crowned he set his summoning, but really didn’t want it to be an open season on summonings. So one of his ‘ingredients’ is a drop of family blood (not specifying if it had to be those he considered family, or blood family) with provisions in place so that Danny would be able to tell if it was being forcibly taken or not through the summoning spell. The cult captures the Batfam and uses Damian’s blood to summon the Ghost King. Who arrives, a little confused. 

He’s even more confused when he sees Batman and Co tied up. Ghost King Phantom peers at Batman, not even paying any attention to the cultist. “Did you call?”

Batman grunts a no and jerks his head to the cultist.

Phantom redirects his focus back to the head Cultist who starts to do a grand speech about glorious power. Phantom interrupts him to ask “How did you get my summoning?”

The Head Cultist lights up with pride, “I have a spell that was able to transcribe your summoning, we used another to make sure we got the right ingredients.”

After a little bit of back and forth the Cultist admit that none of them actually understand the language that they used to summon Ghost King Phantom, nor do they know why they needed the ingredients they did.  Ghost King Phantom pinches the bridge of his nose as he laments that cultists have gotten so damned stupid. Phantom asks each cultist what they hoped to get out of this: 1-13 said they wanted power (in reality the head cultist had a hyperfixation on using the spells he used to transcribe the summoning and gather the ingredients and wanted to see what would happen), number 14 was paid to be there; Number 14 was also a little pissed that the people paying her were not doing basic research so that they knew who or what they were summoning. The Cult thought 14 would be an auspicious number. 

Phantom, now curious, takes a brief interlude (after restraining the other 13) to get more information on 14. She was given $200,000 to be part of the circle. She had a magically binding agreement saying that her soul was not to be offered as payment, that there would be a 5 year moratorium on destroying any planet she happened to be on, and that she could not be targeted directly or indirectly by the cult after they gained power. She was also a former Pre Law Student with an interest in contract law. 

Phantom recruits her for Justice League Dark, even going as far as calling Zatanna down to take her back to the Watchtower.  After she was gone he turned back to still tied up Batfam to apologize. He went to say that Constantine had agreed to go to therapy if they could find a way to fix his Contract/Soul issues, of which there were so many (some of the pieces of his soul had been sold multiple times, other were sold as a larger piece then resold by Constantine in smaller pieces while the contracts for the larger pieces were still active, a half dozen of the ‘your soul belongs to me after death’ type contracts had defaulted on the demon's side before they defaulted on Constantine’s side, one piece of Constantine’s soul-in theory a downpayment on a contract- may or may not have been straight up stolen, then sold by a metaphysical fence three dimensions over and might be in the soul equivalent of The British Art Museum) and that Phantoms sister has been eagerly waiting to study Constantine psyche under a microscope. So a Pre Law student with an interest in contract law was too good a find to pass up. 

After untying the Bat fam, Phantom turns to Batman and says that Phantom really does need to figure out how the idiot cultists managed to summon him, so he needed the cultists for a bit to go over what exactly they did and said but after that they could be arrested.  One of the remaining cultists, not the head cultist, objected to being sent to prison. Without missing a beat Phantom shrugged and said he could throw anyone who objected into a hell dimension for a while, clarifying a while could be anywhere from three days to the heat death of the universe. 

The cultists were more cooperative after that. 

Red Robin suggested that the Bats stay too, since it was also in their best interest to figure out how Damian managed to be an ingredient in Phantom’s summoning.  

Phantom goes over every step of the preparation, the spell to know the ingredients, the spell to transcribe the summoning, and the words themselves all the while sighing every so often in irritation at the downward spiral of cultists in general. 

Despite a cacophony of errors including but not limited to:

 -Mixing the ingredients for the ‘paint’, which the instructions specifically said to mix on site and only as needed, early and storing it in one of the cultists bedrooms (Phantom:...you know that mix is highly hallucinogenic, right?/Cultist: Is that why I’ve been followed by a pink bunny for the last three days?/ Phantom<sighing>:Yes, that is why you have been followed by a pink bunny for the last three days) 

-Adding additional runes to the summoning circle, specifically the runes for sacrificing someone (Cultists: The picture of all the other circles had those rune, we figured it was a typo/ Phantom: it wasn’t)

-Inverting one of the added runes, which switched the party receiving the power and the party being sacrificed (Phantom: Because of those runes, I am able to eat all your souls for the purpose of powering Batman and his entourage/Batman:Please don’t, they all give me enough headaches without getting powers/Phantom:looks like you are all in luck.)

Despite these errors the summoning actually worked exactly as intended. So Robin makes the suggestion that they must have some sort of blood relation.  Phantom shrugs and says that he always thought he was an orphan. One of the birds goes “Thought?”. Phantom smiles sheepishly and says that his sister thinks that Phantom escaped from a cult, but that he has no memories prior to being found by his parents at age 9. He also wonders how closely related he would have to be to someone to show up as family.

An offer is made to go to the Batcave and check with a DNA test to see how closely related they are, which Phantom accepts. On the way there Spoiler asks how one gets a Half Ghost. 

Phantom, who is very blase about Death having a near Danny experience, says: Well, you take a 14 year old idiot, yours truly, put him in what he thought was a non working portal to the realm of the dead, add in an accident that caused him to hit the on button that was inexplicably on the inside. And I do mean inexplicably, to this day my parents still don’t know why they put the on button there. It turns out having a portal to the dead open on top of and through you has some really weird side effects.   

This is a slightly worrying answer but frankly masked heroes/vigilantes don’t have a great grasp on normal anyway and Phantom assures them that his parents got much better about lab safety afterwards.  This dovetails into a very casual discussion between everyone about what everyone thought was the most painful way to die and which kind of events sucked the most to live through. 

They get back to the Batcave and Phantom transforms back into Danny (to get the most accurate comparison. Phantom's blood is mainly ectoplasm which would mess with the DNA test, Danny’s blood still has ectoplasm but much less).  Everyone stares at Danny, before Nightwing makes a joke about Robin and Danny sharing a face.  

At the minor cajoling of Nightwing, supported by Agent A, the Bat Fam unmasks. Danny blinks at them and says to Damian ‘Hey, we do share a face.’

They start the blood test. Everyone is taking bets on how close they are related and from what side. This is all still very casual, very much an air of ‘what a weird coincidence’. 

The blood test comes back twins. Everyone looks at the test, then back at Danny and Damian, then back at the test. Without needing any discussion Bruce runs the test again, despite the fact that the visual clues do indicate it was correct the first time.  It still says Twins. 

Damian is both baffled and a little offended. He did not know he had a twin out there. In theory, if Danny left the League at 9 Damian should have some memories of him. Most of the Bat fam thinks this is another case of Talia being a lying asshole.  Cass peers at both Danny and Damian, and signs that something feels strange about the lack of memory (Oracle puts forth the idea that it’s possible they were raised apart in the league. Damian is sure his mother would have told him if he had a twin).  At some point magical memory manipulation is brought up and they contact Zatanna (masks having been put back on, though Danny remains in human form), who comes down gushing about the 14th cultist, whose name was Rachel, who was already plowing through Constantine contracts and already found a clause that would let Constantine reclaim one of the shards of his soul.  

Zatanna is able to find the spell that hid the memories of Danny in Damian's mind.  She warns that it looks like it affected more than Damian and breaking it would remove it from everyone who was affected. Damian looked for Danny’s permission first (as they did not know who or why the spell was cast- it could have been for Danny’s protection). Danny gave the ok and Zatanna removed the spell. She left quickly so that the Bats and birds would feel comfortable showing their identities again.

The effect was immediate. Damian went pale and teary eyed (due to the spell he was never able to process the ‘death’ of his brother, basically the trauma spent the last eight years festering under the spell) and whispered ‘Dante?’ before lunging to pull his twin close. Jason was a little dazed (he had a few memories of seeing the demon twins together, at a distance). Danny, whose amnesia was not because of the spell, was unaffected but still hugged Damian, who was now clutching at his brother and crying. 

Far away Talia sat straight up from a sound sleep. Her mind flooded with memories of her precious second son. The son who was murdered and has remained unavenged for 8 years. She quickly made arrangements to head toward New Jersey, she would stop and see Damian and invite him on a hunt. 

It becomes clear quickly that Danny would be staying in the manor for at least the night, Damian did not want to let go of him.  He calls his parents and gives them a brief rundown of the situation (was summoned by weird cultist, found blood family-a twin brother and a father, twin brother was bespelled to forget he had a brother and breaking the spell had made him clingy, would be staying in Gotham for a bit). 

His parents run through a Jazz created set of call and response code phrases to make sure that Danny, and now his brother, were not being held by the cult they presume Danny escaped from. After Danny gives the all clear phrases, Maddie asks to speak with his Biological Father.   

Danny hands the phone over to Bruce, where Maddie cheerfully tells him that He and his entire family would be bringing Danny back to Amity Park on Sunday (it was a Thursday, but it was also summer so Danny could stay for a few days) and staying for dinner, that Maddie, Jack, and Jazz all had some concerns about Danny’s condition when he had been found, that any of Danny’s siblings (making it clear that this also included anyone Damian considered a sibling) were now one of her children as well and if Bruce was or became a threat to any of her children Maddie would kill him, and should Bruce pass her vibe check they could discuss shared custody of the children.  Then, without changing tone, asks how many she should be expecting for dinner on Sunday. 

Bruce answers and hands the phone back to Danny, reminding himself that he had gone toe to toe with actual Gods, he should not be intimidated by a cheerful voice on a phone. He is also trying not to think about the fact that he had acquired yet another child he had not known about. Not to mention running through everything that Phantom had ever told him and trying to stave off several retroactive panic attacks.

It takes a bit but they get Damian calmed enough that they are able to get everyone upstairs, where Danny ends up sharing with Damian (who is still working through eight years of trauma and panics if Danny is not right there). 

On Friday, Talia gets in contact with Damian about hunting Dante’s murderer down. Once Damian assures Danny that Talia was not his murderer (as he could now remember them hunting for Dante’s murderer and their combined grief) and did love him, Danny was willing to meet with Talia.  The Bat fam insist on going with the twins to meet with their biological mother. 

Talia takes Danny being there about the same as Damian did.  Not even Bruce had ever seen her cry before.  She, in her own way, practically begged to be allowed to stay in Gotham with her sons for a bit. Bruce agreed and arranged that she would also go with them to Amity Park to meet Danny’s family. It also takes Talia about 45 second of thought, now that she is not blinded by rage and grief,  to realize that the only person who could have arranged Dante’s murder would have been her Father, and that he was probably the one responsible for their magical memory loss as well.  Tim might have his issues with Talia, but he actually hated Ra’s more; they started scheming together to help Talia and Damian express their displeasure over his actions.

I do want to note, Danny does not start getting memories of being Dante. Those memories are gone as a result of head injury and trauma. While both Talia and Damian would prefer if Danny remembered them, they are so pleased that he is actually alive, as it were, that they are not pushing him.   

When they bring Danny back to Amity Park that Sunday, Jack and Maddie greet all of the ‘kids’ (Dick, Jason, Tim, Damian, Cass, Duke, Steph, Barbara) with specialized weapons, non lethal but will knock out a human quickly  and customized to each child's preferred weapon, hugs, and the family Fudge recipe (which they also give to Alfred) for each of them. Plus gear to prevent being overshadowed and an offer to upgrade all of their current armor and gear.  Talia and Maddie, after a quiet heart to heart, got along frighteningly well (there is a brief discussion about Ra’s and Maddie increasingly creative threats). Jack gets in loud, delighted conversations with each of his new children, somehow finding a special interest for each of them to ask questions about.  Damian is able to step away from Danny for a bit to get into a discussion with Sam, in which everyone decides that they did NOT actually hear the two of them planning some kind of eco terrorism campaign that would end with Lex Luthor broken and crying on the ground.  Tucker and Barbara are enthusiastically talking about hacking while Tucker promises to introduce her and Tim to Technus, who would be a huge fan. Jazz is chomping at the bit to put together psyche profiles for each of them so she can be the best sibling possible. 

At some point Vlad comes in (he had mellowed out once he, Jack, and Maddie got together. It turns out he had been pining for both of them but convinced himself it was only Maddie) and booms that he needs to come meet his brother Bruce. Vlad, knowing exactly how Jack can be, sighs a little and asks how long Bruce Wayne has been his brother. Jack responds cheerfully since he brought Danny back and they realized he was Danny Biological father (Maddie had not asked Bruces name nor any identifying information during her threatening phone call. Jazz despaired).