"Really?" Don't act so surprised, maybe. He schools the mild surprise on his face, then rallies some actual composure. Dumb commentary aside, he looks shockingly confident when he steps forward, offering Steve a hand.

In formal greeting, sure, but there's a note of gratitude to it, too; like he's making a pact on that trust. "You can call me Hawkeye."

Nerdy. But if he's got some of Cap's secrets, it's only fair to trade off — even if it doesn't come across as more than a nickname.