I seriously would like to put Peter in a situation where he absolutely has to undo his deal with Mephisto and I think a good twist would be if it came out his soul belonged to Mephisto and this information was kept from him. I think a good way for it to come out would be for in a Spider-verse event a new villain and version of Spidercarnage was introduced. Like a version of Spidercarnage that was also part ghost rider and other threw his Mephisto.
I figure the plot could be Spidercarnage absorbing worlds into his own version of hell and attack Peter's world with an army of evil heroes. I also like the idea of Spidercarnage taunting Peter and tormenting him saying "I'm actually doing you a favor you see you will become me. It's an inescapable fact you die become Mephisto's whipping boy and when the symbiote and you merge you will become worse than the devil himself. This destiny is coming and has been coming for you since you made that deal."
I also just like the idea of Spidercarnage taking on a devil type of role and becoming an ever looming fear for Peter and his universe. Plus the idea of everyone being trapped by destiny even Mephisto is really interesting to me especially if Spidercarnage out right forced Peter to remember everything and berated it for it. I just love the idea of Peter being forced to watch as an alternate him commits atrocity after atrocity while being told he's Peter's fate and that his world was already going off the rails because of the deal. With Kindred just being the beginning. I mean Peter really made a selfish choice with that deal and I really would like for the deal to be made into a problem for him he has take care of and for him to need to undo it some way.
I've just always wanted Peter to have a moment like this where the world is falling apart and it's because of him