Hey, ya got me thinking.
Peter could wake up in some burial grounds, ala Kraven Epic, and heads back to USA. But not on an Avengers jet, on foot, sea, motorcycle.
He gets home to find Ezekial drugged him, left him for dead, then with some magic mumbo jumbo (can deal with this for a bad guy) Ezekial lifted some essence from Peter.
He also knew he'd lose himself and be more like Peter during the transformation, and with his assistants working around the clock, his objective of getting close to the Avengers' cash flow would be fool proof. Just "be" Peter and don't think about anything else, until your assistants snap you out of it.
His assistants had a bull ***t Morlun go after him so he'd let out the stingers and evolve into an even bigger threat.
So he's been posing as Peter all along and he actually has those Stingers in his arms, he had sex with MJ
, he has been PURPOSELY kissing Iron Mans' ass, 'cause he is the Lex Luthor of the Spider-Man universe, not Osborn.
Hey "It's business kid."
This way, every crap thing that is out of character or not possible (stingers in forearms, hunter mentality) was actually inherent to Ezekial, and Peter was the product of fate and a science radiation experiment gone awry for him and a little Spider all along (duh).
Peter comes back to his Aunts' house blown up, his Aunt sleeping with the Avengers butler, Iron Man thinking he was Peters' boss, and a new Tougher Villian.
All that and he was not even there for the Cr*pfest which was Sins Past.
So he can immediately smell bull**it right away.
He'd say "I slept with Gwen, the Timeline doesn't fit, MJ, you got suckered and I am pissed at you for not telling me this, even though it isn't true, what if it was, you could have left 2 innocent lives to perish, that I could have saved."
But the Twins end up being recent genetic constructs of Gwen and Norman DNA, test tube style and therefore the only Sin left was MJ being suckered and Ezekial too ignorant to know better.
Bam! Obviously a little tweaking would be needed but it fixes Peter's wimpy attitude, Sins Past and the Other in one swoop.