beta
This trope where the older, usually much older, uke raises the much younger seme to be wildly sexually obsessed with him is a trope that normalizes grooming. You're going to say "there's no grooming in the story!" But of course there was grooming, you just don't see it. That's how grooming works. Plus the story is told from the POV of the groomer (the uke) and why would the groomer think they did anything wrong.
The whole point of grooming is that it is something invisible that is done to children in order to make the children think they are sexually attracted to the adults. A child who has been groomed will often beat the initiator of sexual contact because they have been groomed into thinking it's something they want. The sexual obsession that these groomed children show is a symptom of grooming and not a reason to think the groomer (the uke) is innocent.
Now there's going to be some idiots who are going to respond to this saying "he didn't raise him!!!" And to that I have to point out that you probably don't have any older siblings or aren't an older sibling. A sibling who is 10 years older than you very much raises you, even if it's not their primary responsibility. They are still very much an authority figure who is constantly there and has power over you.
A cousin that is adopted by your family is no different than a sibling. Adopted siblings are still siblings.