What things did Murderface do for fun? Because during MAXIMUM CHRISTMAS it almost seemed that the way she spent her recreation time was watching already dry paint continue to be dry (I assume she was actually thinking). And of course Murderface was alone instead of with someone tolerable.

Yes, you got it. She spent a lot of time by herself thinking, trying to piece together the patchwork memories she half-remembers every now and then. It's a lot for her to figure out. But as for fun activities she usually just read books or helped maintain the Officio's armory. Until she got to drinking of course!