Clint Barton. He had been head of Cabin Seven during his days at camp, and was one of the best archers Camp Half- Blood had ever trained. He was also one of the rare half- bloods that had made it to adulthood. In short, he was a bit of a legend in the Apollo cabin.

But no one at Camp Half- Blood , apart from Chiron, had worked out the connection between the Avenger, Hawkeye, legendary shield agent and assassin; and Clint Barton, the son of Apollo.

No one, that is, until Will Solace was sent to stay with his half- brother...

The characters belong to either Rick Riordan or Stan Lee.
*salutes*
I only own part of the plot. The crossover part lol.
*cries*