Mouser's nemesis paid some visits over the last couple of days. They seem to tolerate each other, no hairs standing upright, no claws extended. They've been checking each other out from a distance (2 meters).
Today Bonny (which I presume is his name) darted out of the bushes when I wanted to sit in the garden. I fetched Mouser to see its reaction.
Velvet Claws stayed in the veranda. Bonny stayed outside the veranda.
It looked a lot like the mirror-act mime actors perform.