Well I figured since Lost Cause was considering Spider-Gwen that would open up Peter Parker.  Since his a genius I thought it could actually be a fun concept to make him into Mr. Fantastic where he joins the Future Foundation think tank program which also has Victor Von Doom and Reed Richards.  They work on and go into space for a space station project.  Something goes wrong and they get blasted by cosmic radiation before they can get to an escape craft.

Plus it could make an interesting situation where if Peter and Gwen date.  Peter could be the popular hero as Fantastic and Gwen as Spider-Girl/Woman would be the disliked one.  Adding a big kink into their relationship.  Plus since you can edit characters backstories, with my RPs at least and this one sounds like it as well.  You could certainly have someone like Wally West for the DC side of things.