Warriors (джен)

Loki dies by the hand of Thanos and is offered a deal by one of the three Fates, Atropos. In exchange for defeating Thanos, he gets sent back in time to just before Thor's coronation.
Tony Stark snaps his fingers and Thanos' armies turn to dust. They won but he dies with a whole lot of regrets. Atropos appears before him and offers him a deal that in exchange for defeating Thanos before he can snap, he will be sent back in time to the beginning of the Stark Expo in 2010.
Peter Parker is grieving the loss of not only his mentor/father figure, he is also grieving the loss of his last living relative, his Aunt May. She died of cancer three years after the snap. He is crushed with grief so when Atropos appears before him with the chance to fix everything, he jumps on it and is sent back to 2010 with the bonus of his powers.
Each of them think that they are alone in this journey through time but it doesn't take long before they come together and form a make shift family.