^Except it's still a deal with the devil, which is kind of anathema to the whole "hero" thing. And, again, it's completely illogical that the most brilliant minds, most powerful sorcerors, and most godlike cosmic entities in the Marvel universe couldn't fix a simple bullet wound even though they've been shown to be capable of far more miraculous feats in the past. And saying that it's just May's "time" doesn't cut it. It's a hollow excuse. If that were the case, then Mephisto shouldn't have been any more capable of changing May's fate than anyone else. It's grossly inconsistent, arbitrary storytelling. There's no legitimate reason why a deal with the devil would've been Peter's only possible recourse.
Talking about deals with the Devil....
I just finished reading Showcase presents The Brave and the Bold: Batman Teamups Vol 2
and the last story has Batman fall down into a steep well. On the verge of drowning, he says something like "Batman doesn't want to die! I will give up my soul if necessary" (yes, third person self-reference!). The reason he doesn't want to die is a child's life depends on him being able to get out of the well and *do something*. Lucifer (An old guy with a limp whose shadow looks like The Horned One with a Trident) then helps him. Sgt. Rock is the other team-up character. Rock has mistakenly thought that the Lucifer-like figure is Hitler still alive. Lucifer claims that Batman is now a minion but Bats reneges on his offer. The story ends with Lucifer's vehicle going up in flames but the last panel shows Lucifer walking off into the gloom with the horned shadow very apparent.
Weird story. But the art in the book is gorgeous (even in black and white). Most of the stories are ghostly/horror/eerie stories. There's one where Thomas Wayne is experimenting with bringing people in limbo back to the real world. Which is a wrong thing to do. So Thomas and Martha's souls are in limbo now (for doing wrong experiments) and Batman keeps getting possessed by the ghost of Somebody Port-A-Gee (Portuguese sailor), who's trying to get the limbo people back into the world. And eventually Thomas and Martha's souls get released from Limbo. The Teamup is with Flash ( I know... what does The Flash have to do with all this stuff!!).
But deals with the devil (Faustian bargains etc) aren't unheard of... even for as self-less a hero as Batman.