This is what I found when I walked into the kitchen this morning. Mim has turned her big brother into a "pack amoeba." It's like a pack mule, but with fewer cells. A lot fewer.
Frankly, she's lucky that she has such a laid-back brother. He doesn't do everything she says, but he certainly does a lot more than I would. One day he's going to assert himself and give her the shock of her life, but so far they play together very well, with only the occasional spat that requires parental intervention.
I do frequently hear things like, "But I don't want to be a Pokemon!" from Mim or "But I don't want to build with Legos!" from Zaya. By and large, though compromise is the watchword, and when it isn't, I go on my spiel about sibling love and getting along and not driving Mommy crazy. It generally does the trick in that they would rather play something with each other than listen to me lecture. Whatever works, really.