The following vignette perfectly summarizes the boys' relationship right now:
I came out of the shower and they were playing doctor in the rose room.
Erik: checked Adin's right ear "Looks fine."
checks other ear "You have a carrot in there.
checks first ear again "You have a potato in here".
Puts blood pressure cuff on Adin. "Looks good."
Looks in doctor bag, pulls out plastic bandaid. "Are you ready for a bandaid?"
Adin: backs away, cringing. "Noo! I'm not ready."
Erik: gets really mad, "Well you need a bandaid and you're stupid."
So basically, they alternate between playing together wonderfully, and fighting over things like a glass of water. (Anne: "We have plenty of water! You don't need to fight over that glass!") I learned that they are not yet able to control themselves better when I threaten them with Santa watching, so I have given up.
Merry Christmas everyone!