Captain and Bill were besties in their foster hospital and the staff there preferred if they were adopted together. I said ok and that is that.
But their relationship isn’t without its complications. There is some jealousy. Billy likes toys and tends to assume all the toys are his. So when Captain decides, every once in a blue moon, that he would like to play with a toy, they fight. Or when I rub catnip all over the scratchy toys, which Bill assumes are his, and Captain wants a sniff, they fight.
Or, apparently, when Captain is hiding under the bed planning his attack and Bill is on top of the bed and hears him wheezing… well, eventually they fight but first, this happens:
Then eventually we figure out that Captain’s under the bed. Humans are slow. We just thought Bill was being weird again.