Biggest Betrayal: Using his death in order to displace Odin by putting him in a old folks home and prtending to be the All-Father. That's just low, man.
Most Heroic Moment: Joining the Revengers and holding off the Beserkers so that the Asgardians could escape.
Loki/Clint Barton Team-Up: It would be hilarious. Especially in light of the fact that they haven't met since Loki mind-controlled Barton.