Nick Fury, the leader of S.H.I.E.L.D has gathered the Avengers in hope of unmasking the mystery Spider-Man, who seems to make attention for himself saving the city. Fury puts the order out for the team to take Spider-Man in without the possible out come of a battle and get him to join.
While behind the scenes. Tony and Steve are searching for a new addition to the family. A child to adopt. They search amongst the orphanages trying to find the right one.
Enter Peter Parker. A 15 year old boy without any hope of being adopted. Seeing the fact that no one wants a kid who's already that old. Being the oldest in the orphanage isn't really the most amazing thing either. Add onto Peters issues and secrecy for more fun.