Parental Braig/Xigbar (aka Dadbar) Headcannons
Inspired by @eks-art
It started with Vanitas. In Braig's defense, he's pretty sure it isn't kidnapping if the kid's being abused.
Because Braig kidnapped surprise adopted Vanitas, he and Ventus never fight and form the X-Blade
However, Eraqus still dies, Terra still gets possessed, and Aqua still falls into The Realm of Darkness
Therefore Braig brings Ventus home, because he can't leave a child without a home
Vanitas misreads the situation and assumes he's being replaced as Braig's adoptee apprentice, and runs away ("You brought Ventus here. Obviously it's because you want to replace me with him! Ventus is the one everyone loves! I'm just the unwanted dark half!" "Kid, that is untrue, and I'm starting to think I should invest in getting you therapy. You are not unwanted.")
Then Subject X (aka Skuld) gets found
Braig sees Subject X, sighs, goes home after his shift, explains to Ventus and Vanitas that he's going to bring another another kid there and that he's not replacing either of them ("That was one time!"), and then kidnaps surprise adopts Skuld
So much Union Cross related angst
Ventus, Vanitas, and Skuld get worried when, one day, Braig doesn't come home
He returns in two days and explains the whole "Xigbar situation"
Then Radiant Gardens falls to darkness (becoming Hollow Bastion). Xigbar sort of parents them while the three of them are living in Twilight Town
Kh 1 happens and Xigbar has to check on his (now 26 year old) sons charges (and he checks on Skuld, too) when he sees Roxas, only to find them with Sora ("WHEN DID YOU HAVE A KID?!" "I DIDN'T HAVE A KID!")
Anyway, Sora, Roxas, and Xion have been kidnapped adopted into the family
Then Sora's memories get nuked by Naminé and Roxas and Xion go poof. The loss of Roxas hurts everyone, and Xion going forgotten leaves an impact, since this found family weird friend group always feels like someone is missing
Imagine the protests when Sora (and Riku and Kairi, although they haven't been kidnapped adopted into the family. Yet.) Has to go home
Just. Dream Drop Distance's whole premise being something that Yen Sid is shouted at for ("YOU SENT TWO CHILDREN INTO SLEEPING WORLDS?! TO MAKE THEM KEYBLADE MASTERS!? TO FIGHT IN A SECOND KEYBLADE WAR?!")
Xehanort finding (and subsequently trying to recruit) Vanitas
Xigbar betrays Xehanort when Xehanort tried to get him to hurt one of his children during The Final Battle(s)
Literally just The Foretellers being summoned back (Ava included this time) and immediately being pulled into this wierd found failed that Luxu/Xigbar/Braig formed as aunts/uncles