I have come to the conclusion that it is no longer safe to clip the nails of Middle Son's pointer fingers. And perhaps his thumbs.
He is generally resistant to having his finger nails clipped (for some reason toe nails are not a problem). I clip them as part of his night-time grooming routine. We floss, brush teeth, and shave with an electric razor. Then on some nights we clip nails. When I get the clippers out Middle immediately presents his pinkies and lets me clip them. Ring fingers are usually not too difficult. Sometimes the middle fingers are ok. Usually they are a challenge.
The pointer fingers are hugely difficult. I try to hold his hand steady, with my fingers under his pointer so that the nail is exposed. He takes my other hand and holds it so that it blocks my line of sight. He digs his nail into my hand so that I can't get the clipper under it. Then he starts jerking around.
Last time I tried to clip the pointer, My Beloved Wife came in to help. We wrestled with Middle for about 5 minutes. Then I called a halt. We weren't getting anywhere and Middle was becoming more and more agitated. I was afraid he was going to jerk too hard and dislocate or break my fingers (or his).
He will let me use an emery board on his pointers and thumbs. A few nights ago, after I spent some time filing his middle fingers I was able to use the nail clipper on them. Still couldn't get the pointer.
I've told the ABA therapist that we are starting to work with that this is a high priority. If I can't clip them safely, they will get very long. That poses another sort of hazard that I'd rather not have to deal with.