James "Samaro" Potter is likely the father of Harry "Vampire" Potter (in Chapter 35, Vampire's father is noted as Serious Blak, but this is likely an error).
Samaro attends Hogwarts in 1990 and is a member of Slytherin house. He is named Samaro after the female character, Samara, in the movie The Ring. He is the guitar player in a "goth band" called XBlakXTearX along with Snap, Luscious Malfoy, Serious Blak, and later, Ebony Dark'ness Dementia Raven Tara Way.
The band plays a concert with Marilyn Manson in Hogsment (the 1990's name of Hogsmeade). However, when Luscious accidentally begins playing the wrong song, Samaro begins shouting and calls Luscious a "fuking ashhole!1" Samaro then pulls a knife on Luscious and tries to "shoot off his arm." Ebony jumps in front of the bullet (it appears that the knife is really meant to be a gun). Later, Ebony learns that Snap has the ability to possess people; Samaro only tried to murder Luscious because Snap had possessed him. During this scene, James appears to be alive, but later on, it's mentioned by Ebony when she is trying to get Satan and Hedwig back together that "now Harry's dad wouldn't die", so James' appearance in the present was likely a mistake. Also, he is not listed amongst the people entering the hospital wing to visit Ebony, so Tara likely meant his dialogue to go to Lucian.
The last mention of Samaro is when he, Hedwig, Satan, Serious, Snap, Luscious and Ebony are called into Dumbledore's office; Dumbledore threatens to throw them all into Azerbaijan for being Satanists.
A peculiar note is that even in the past, characters already know he will be Harry/Vampire's dad, and Lucian will be Draco's. Whilst Satan knowing this could be explained if he was supposed to be the future Voldemort all along, Lucian tells James "Draco is never going to be friends with Vampire now!".
Naturally, this depiction of James is incredibly out of character. In canon, Lucius did not attend Hogwarts when James, Snape, or Sirius would be in their 7th year, and it is well known that James and Snape did not even remotely like each other. Lupin and Pettigrew aren't mentioned at all, and they actually would have attended Hogwarts in the 1970's. Voldemort himself attended in the 1940's, and obviously was not friends with James whatsoever.
Trivia
- Samaro is the name of a town in Pakistan which used to be called Jamesabad (literally "Jamestown"). It is highly unlikely Tara knew this, however.