I have one child who is a wall flower (not unlike her mother) and another who no-one can forget. In fact, most people's first comment about Brennyn is usually along the lines of "wow, she has quite the personality".
Avery is the serious one, Brennyn spends most of her time trying to make people laugh (especially if she thinks it can get her out of trouble).
Somehow, though it works for these two. They may be complete opposites (which can be exhausting for Mom at times) but they love spending time together. Of course, Brennyn has wanted to hang with her big sister since day one but trust me, the feelings were not mutual until a year or so passed. Now they really are best of friends, well for the most part. I'd be lying if I said they still didn't fight like cats and dogs, it's just that the fighting portion of their day has gone down dramatically.

On an unrelated note. Today Brennyn said "Mom, I love you". "I think you're a hot chick". Almost fell off my chair laughing!