You have just described me ... well, sort of. A bit different, but having the same principles.
I've spoke about it elsewhere. Why this is? I can't tell you for the life of me. I have had intense, obsessive and overwhelming preoccupations with subject matter that goes beyond the normal interest things, such as wanting to discuss it and research it. Yeah, there's those things, but there's also this empathic feeling. The subject matter, which ranged from things like dogs and fish to ocean waves and rivers to even wood and fractions to even my own disorder, had constantly shifted when I was a child. I felt this emotional connection that would rise up and down in intensity. Nowadays, it doesn't change as much, and stays primarily with rivers, though there are at times minor changes to something else, but it seems to stay around the concept of rivers.
With me, the word associated with the subject matter has the ultimate emotional connection, and occasionally so do pictures. So, I tend to talk to these pictures and stuff, sometimes for a couple of hours, literally holding a true conversation, talking and answering myself back. It's part of why I talk to myself.
I, too, find myself wanting to protect anything surrounding the subject matter. As for rivers, I'm a member of a couple of environmental groups devoted to river protection and preservation. I am not so personal with other people with this, though, tending to keep it to myself, though I can get on lengthy discussions with people who are interested in the same things.
It shouldn't be a problem. With me, it was more organized. It sounds more disorganized with many others on this post. But, anyhow, the concept is the same. Some may grow out of it; others may not. Don't worry about it, unless it proves to become a real distraction, say if it interferes with his school work or something. Maybe it will actually get him involved in something that will keep his interest in the near future. Maybe he'll be interested in some sort of chef work or something. Who knows?
- Ray M -