Originally Posted by AwkwardMD
You're asking for a lot from that scenario. In your proposal, the son has to remain friends with a peer while also accepting that peer as a father figure, OR lose his mother as a parental figure. Like if mom just becomes an older woman in his life.
Or identifying with the friend as a brother he perhaps never had? Seems to me the OP might be looking for a loving little family with a mom and siblings.
Somehow, I don't expect this will be a common incest theme. The OP might need to write his own story.