Eobard Thawne (Arrowverse)

Issac is a character from Once Upon A Time, who also goes by the name of "The Author". He was the man who wrote the entire Once Upon A TIme Series in universe. thus everyone was a cosmic plaything to him as he wrote things to happen to everyone for the purpose of a good story. Which he's been doing with multiuniverse stories, writing characters the way he sees fit and writing them off when they're done with. He was given the role of Author in December 15th 1966 when the previous author passed away. Ever since then he was writing stories  the "Author" was only supposed to  record  events, but He gained a God Complex and began manipulating events for the sake of better stories to record so he got trapped inside his own book as punishment. However he will escape due to something accidental on part of one of his characters.

He needs a magic quill to able to write stories, but don't let this assume without it he's nothing.

His Next book is something about where Heroes are Villains and Villains are seen as heroes and his motvations for this are that heroes reminds him of all the people he saw who were successful and had happy endings, while he himself wasted away as an unknown writer. Because of this, he's more than willing to  tear apart entire worlds  just so he can come out on top.

An Author can resurrect a dead character if they die in a story that has been written.

TGTTA 2
Issac appears as one of the four main antagonists of the story, alongside his partners The Joker and Deathstroke and the Time Masters. Where he forms a syndicate of many of the past villains from the past stories to orchestrate the defeat of the heroes and plots to recruit new villains. While working on making a new magic quill to start writing the story where villains win and heroes lose and die.

Friends: The Joker, Deathstroke (Arrow), Blaine, Theo Noble, Dick Roman, The Ogre, The Pied Piper, Uka Uka, Brother Blood, Tarus Bulba, Darkwarrior Duck, Eggman Nega, Vilgax, Porky Minch, M.Bison, Terrance Lewis , Sketor, Asura (Soul Eater), Dr.Weil, Moriarty, Malachite, Kingpin, Gus Fring, Skylar, Rodrigo, Zelena, Ra's Al Ghul (Nolandverse)

Enemies: Slade Wilson, Anti Cosmo Cosma, Bender Bending Rogeireuz, Skipper, Phineas Flynn, Isabella Garcia Shaprio, Jimmy Neutron, Suede, Discord, Jorgen Von Strangle, Marceline the Vampire Queen, Finn the Human, Django of the Dead, King Julian, Celes Chere, Hades, Mojo Jojo, HIM, Sideshow Bob, Bowser, The Flying Dutchman, Black Curveo, Technus,Ventress, Rick and Morty Sanchez