We moved a lot growing up...to the point that the only constant from year to year was family and the only playmates we could be sure to count on were siblings. I happen to have three of them - two of which are older, one of which is younger - and I love them to death. The relationships are not perfect - there have been many screaming matches, months of silences, and moments where I could have killed them (and vice versa) - but in the end none of that matters.
That said, O wouldn't be O without a little mischievousness going on. Her new favorite thing is to tell me all of the things that C has said to her (did you know that my genius baby can talk?). O likes to tell me "mom, the baby called me a poopy head" or "mom, the baby said she doesn't want to go to the supermarket" or my personal favorite, "mom, the baby told me that she doesn't like you." Yep, she's trying to get her infant sister in trouble - that sounds about right for a sibling relationship.