I was playing Outskirts, in the courtyard bit at the beginning. The two Hunters come in. I run up to a Marine and grab his sniper rifle.
"Oh, so now you want MY gun?!"
Carrying on, I snipe one Hunter. I look round to find the other, only to find the Marine going toe-to-toe with it. Using the battle rifle I gave him. Just as I'm trying to line up a sniper shot, over goes the Hunter.
<- my reaction.
Then the Marine, whilst shooting the corpse, said "It's not that I want to kill you, you're just to ugly to live."
I think I found the Marine that's actually harder than the Master Chief.