Dr. Fyre is a research scientist specializing in Gamma Rays who never though about death until his wife Claire died then he became obsess with immortality.
Doctor Frye was created by Al Ewing and Joe Bennett and first appeared in The Immortal Hulk issue 2 (2018).
Major Story Arcs
The Immortal Hulk
For more information see: The Immortal Hulk #2 - The Walking Ghost
After his wife died Dr. Fyre threw himself into his work and came up with some cancer treatment that he sold to pay the bills but he also used Gamma Rays to create a serum for himself. The serum made him feel years younger and he decided to use it on his son Delbert John Frye. This killed Delbert immediately. Fearing for his life, Dr. Fyre destroyed his papers on Gamma Rays and called the police, telling them he had no idea what happened to his son.
Later, Dr. Fyre noticed his skin starting to glow green and fled the town, choosing to live in a cave nearby. There he killed anyone who stumbled onto him, that is until Bruce Banner found him. Dr. Fyre tried to kill him to but the the sun went down and the Hulk emerged. Dr. Fyre told the Hulk all of his backstory, but the Hulk was still mad at him. The Hulk explained that Delberts body was poisoning the town with Gamma radiation and Dr. Fyre would have to be punished for killing several people.
The Hulk then ripped off Dr. Fyre's limbs and left him under a pile of rumble, still alive and trapped forever.