Shades.
I'll toss one over to Sunstrike. Without his help on Day One, I probably would never have gotten a response to my requests for reinforcements (I've always been a little shy about playing mass numbers of NPCs). He's the reason Jagged Cliffs and Cresent Plains were fortified.
Honorable Mention would probably go to Sam, I think she had the only nearly naked scene in the entire event, and a dually to Hakan and Flare, together they were awesome.
