How do you describe manipulation to a 7 yr old?

[Leish]

I'm trying hard to explain to my 7yr old that he is being manipulated by a boy at school who, historically, has been a family friend for many years. The boy has tried every trick in the book to isolate my son from his other friends and is highly possessive. I am working closely with the school and am off to see the school counsellor tomorrow to give my perspective. It has gotten so bad though that I want to sever the relationship completely and am trying to teach my son to move away from this boy. He did move away from him naturally last year but unfortunately they're now in the same class (and will be for four years now) and he is now this boy's object of possession. He feels a mixture of feeling sorry for the boy as none of the other kids like him, fear that he will be shouted at by the boy if he doesn't play with him and also a genuine bond because me and the boy's mum have been friends for such a long time. Things have deteriorated so badly now and my friend is in deep denial about her son's social difficulties (my son is the most recent of a constant string of relationship difficulties) that I now feel that we need to sever ties. I am trying to describe manipulation to my son but it doesn't seem to be sinking in and wondered if anyone had successfully explained what this is to children of a similar age? Thanks x

I'd focus on behaviours:

Ask your DS why he thinks this other boy would shout at him, is that an okay way to behave, would his teacher think that it's a okay way to behave?

Do the same with other behaviours; if this boy is making him feel guilty look at how he's doing that (tears/I'll be all on my own/I'll tell my mummy) and talk about whether they're okay things to say or the right way to behave.

The bond that is there can be discussed within the concept of people changing as they grow up (use examples he'll identify with such as ways he's changed) and that sometimes, however much loyalty we feel we have to step back to let other grow/change/get help/however you want to explain it.

Good luck though, it's not an easy thing to explain (maybe his teachers could give you some suggestions/hopefully someone on here can suggest a book).