After the credits roll, Mary Jane and Peter are sitting in their favorite diner talking about the events with Black Cat. Turns out that she doesn't actually have a son and was playing Spider-Man the entire time.
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Did Peter cheat on MJ with Black Cat?
Peter has never cheated on Mary Jane. The Black Cat was his on again, off again girlfriend and MJ was nothing more than a close friend during that period. The closest thing he had to a "date" with Mary Jane was a walk in the park in ASM no.
10/13 The Two Become Lovers and Partners. Black Cat would again reappear in The Spectacular Spider-Man in 1983. Peter was overjoyed that she hadn't died, and they immediately resumed their relationship with a passionate kiss.
Despite her antipathy towards men, Felicia feels a kinship with this lone hero; Spider-Man is the first man she felt she could trust and she grows to believe herself in love with him. Felicia looks for a way to earn his trust and continues with the Black Cat persona as a misguided attempt to attract his affection.
The bromance (OK, maybe just romance) between Spider-Man and Deadpool is undeniably strong, so strong in fact that they actually have a shared biological child, appropriately named Itsy Bitsy—who's pretty gross and deadly.
However, in a recent Marvel Comics Senior Editor Jordan D. White lays out the logic behind that choice, explaining that once Peter has a kid, suddenly him acting like a hero is way less justifiable. It's very rare for Marvel or DC Comics superheroes to have children.
Marriage. In spite of Peter and Mary Jane's mutual worry that they were marrying too early, Peter's concern for her safety, and her unwillingness to give up her "party girl" lifestyle, they marry. She adds Peter's surname to her own, making her Mary Jane Watson-Parker.
History. Peter Parker's life presumably mirrors that of his Earth-616 counterpart, up to the point where Peter was supposed to marry Mary Jane. In this reality, Peter decided not to marry MJ and cancel the wedding, which eventually led to him marrying the Black Cat instead.
The main reason for the breakup is that Black Cat was only really ever interested in Spider-Man. Her surface attraction to the costumed web-slinger never matured into actual feelings for the man beneath the mask.
Spider-Man is the first hero Black Cat encounters after beginning her career as a masked burglar, and Felicia develops a crush immediately. Not one to associate with criminals, it takes Spider-Man awhile to return the affection; but eventually, he is won over by Black Cat's charm.
The story arc "Sins Past" by J. Michael Straczynski reveals that Gwen Stacy fell pregnant with twins after having sex with Norman Osborn, a boy and a girl to whom were given birth while in France. Gwen vowed to raise the twins with Peter Parker and refused to allow Norman access.