On August 27th I wrote about how my 3yo was pounding the 2yo and not stopping. We seem to be in that "phase" now. I spoke to 3yo about it when things were quiet, about how he felt about hitting his brother, was he aware that he was screaming for him to stop, and how he wasn't stopping. I asked his opinion about me pulling him off of his brother when his brother was screaming and he wasn't stopping, and he thought it was a good idea.
I was doing that for the last week or so, which caused the little one to play up the victim role more, and to a lot more screams of "Mommy!"
I just remembered a technique I like to use in these cases. It's inspired by the book Playful Parenting by Larry Cohen. When the aggressor and victim are rolling around and the victim is screaming and the aggressor doesn't stop, I pull the victim out, briefly comfort him, and then start roughhousing the aggressor. The more giggles I can elicit, the better.
Ten to twenty minutes of roughhousing can change the whole course of the day.