The Wolverine and the X-Men writer has discussed the forthcoming miniseries, which will tie into Marvel Comics 'Infinity' event.
"This does feel like a little bit of a departure for me, Marvel-wise," he told Newsarama.
"As I'm writing it, it feels like a combination of what I'm doing in Thor with what I did in Scalped. And it is certainly darker and weirder than most anything I've done for Marvel, because it's a villain story.
"There are no good guys popping up to save the day in this. It's the origin of a mass murderer."
Aaron said that this was the first time that the "bits and pieces" of Thanos's origin have been collected in a single story.
"This is the full-on, five-issue, from day one origin story of Thanos," he said. "We know how the guy's gonna wind up - he's going to wind up as this fearsome, cosmic mass murderer. But there will be some surprises along the way."
Thanos Rising #1 will debut in April with art by Simone Bianchi.