i like her but she plays every character the exact same way!

Is it me or has she played the same character in Lost, V and Revolution????
Always some likeable yet enigmatic person who at first you can't be certain of their true intentions but find that they do things that are questionable only because they are trying to protect the greater good and the good people around them????
And while her character is always ultimately caring and has strong convictions, still sort of carries things out in a bit of a detached almost cold sort of way?

don't get me wrong - i really like elizabeth mitchell, but just not sure if it is a coincidence in the roles she has taken recently or if that is just the limits or her range as an actress - even when i think back to the first time I noticed her in gia - she gave that character a very similar feel