Oh aye, they do. Mostly by fighting and getting into trouble together - this morning they woke up before me and, instead of waking me up like they usually do, they figured out how to get into the brownies that I'd thought to be out of their reach - but they do also go adventuring and, you know, play together. It's taken a bit for that to evolve from "playing near one another" to actually playing together, but I'm pretty sure they're finally there.

Oh! And they also go to the bathroom together. One sits on the toilet and the other tells jokes or stories. It's very cute.