OK, so we have had a houseguest for the last week, and she found it very strange that I went running for the camera when I saw Mittens and Frou Frou on the cat tower at the same time! I didn't know what was going to happen, but I was pretty sure something would happen....the cats have a bit of an ongoing war for high ground in the house. It's a strategic war and very rarely leads to a physical confrontation, usually there is just a lot of posturing. With the cats, possession really is 9/10ths of the law, and so whoever occupies the high ground the most stakes a claim.
I won't make any more comments here as it will spoil the ending, but let's just say, there was a clear winner this time.