Milly Thompson
If Meryl is the brain, then Milly is the heart. She is Meryl's partner, and friend. Finding Vash is the first field assignment that she's ever had, and most likely the first assignment she's ever had. I believe that she's under 20 years of age, but acts like a five year old most of the time. She apparently likes Nicholas, maybe--to tell the truth I don't know how she felt about him. An older brother? A best friend? Or a love? I just don't know. There really wasn't enough information given about her feelings toward him, and given her personality, Milly and Nicholas did not do anything major the night before the horrible incident. I will continue to think that way until I see solid proof too.
Milly is incesently happy and gives advice from the heart, but just like Vash, it's always someone else's words, never her own, not that it's bad to put faith in other people's knowledge, but you should also gain your own knowledge instead of allowing other people to feed you wisdom. However, a person who does not listen to their peers is not a wise person, so Milly is pretty wise because of the knowledge stored within her, but she really should discover some things on her own also.
Most people claim that she's sharp, and doesn't know it; I just think she's a lucky guesser. This is only because she figures just one thing out, and that's that Vash is Vash the Stampede, but she never stresses this fact, and I think she forgets about it by the time that they learn the truth.
In truth, it took me forever to like Milly. I was a bit too attached to Nicholas to see past hiim :). However, I'm actually starting to like Milly very much, so it's making the show even more enojoyable--if that's possible.