as most of you may know/remember, I got a shelter cat for my parents.

Initially he was very reserved, but has since warmed up to my father and plays well and does seem to enjoy being near him. Contact is strictly on his terms and you know when you've been "dismissed".

In the last couple of days, he's taken to "ambushing" my Dad's ankles and gets underfoot. Since my Dad has a suppressed immune system, he can't risk cat scratches, and I purposely looked for a gentle cat. He's gentle in all other areas, just has this habit of going for his ankles.

I've done some reading and it looks like it's pent up energy from not being able to go outside (they have a large patio, but no comparison to being really outside). It does appear he had outdoor access in his previous home. He really enjoys playing, so it maybe be a form of play as well.

Question is, how does one curb this behaviour? We've had cats all my life, but we've never had a cat do this. If this continues, the adoption may become a failure and he'll have to either go back to the shelter or come live with me (not preferable at the moment as I already have 2, one being very dominant and aggressive).

It would be better if we can clip his nails, but as soon as we make a move that he's unsure of, he's GONE. I don't really want to break his trust, either, but I'm willing to try next time I'm there simply because he can't keep scratching my Dad's legs.

Any help/suggestion would be appreciated.