Two of my kitties, Karma and Kash, are brothers, so they've always been fairly close and enjoy being around one another. Being siblings from the same litter, they also happen to look out for each other. This includes making sure the other cat is well groomed and clean. If Karma gets anywhere near Kash, he almost always takes it as an invitation to start grooming his brother. It's easily one of the cutest and most endearing things I've ever seen.