While I was out of town last week, the cats bonded with each other quite a bit. The older two, especially Rugrat, will even initiate playing with Lucy. Rugrat has copied Luna's habit of pretending to be annoyed but then coming back for more tormenting. As for Lucy, much of the time she prefers their company to mine. In this and other regards she is more similar to Luna than Rugrat. I'm not entirely surprised - at the SPCA they predicted this would happen, based on their observations.
I'm still the wrestling buddy, though, since the older cats don't really want to roughhouse. This is entertaining when I am awake, less so when it's 5 AM and am awakened by Lucy chewing on my elbow.