Hawkeye was never a SHIELD agent. He's an arrogant, abrasive ex-carnie with his own sense of justice. He's hotheaded, impulsive, and snaky. He's also fearless, selfless, and incredibly loyal. He's also the only normal guy on a team full of gods and billionaires. I find him to be a very likable, compelling character. And Ollie is one of my favorite DC character, by the way. They fulfill similar roles, as the everyman trying to keep the gods honest. Though I think Hawkeye is a bit more repayable than Ollie the left-wing billionaire.