Peter was told to stay put and away from the fight. He was also told not go after Thanos or the infinity stones. He wanted to be useful, He wanted to prove himself. Tony told him to hide to protect himself but he doesn't listen. He see's an opportunity to take down the bad guy and he takes it. ____________________________________ (Everyone is on earth) During infinity war Peter finds himself getting kidnapped by Thanos. Tony and the others go on a rescue mission to save him.