beta
Im interested in the younger brother's angle because its clear that he's transmigrator/reincarnator similar to the MC (And that they may have known longer than the MC). Especially because everyone thus far in the MC's memories have had a lookalike in the novel, like its obvious that the Sunbae in the MC's memories is the ML, and even his bestfriend in the novel looks and acts like his bestfriend in his memories (short hair, energetic personality, etc).
So, theres a chance that the younger brother could actually be an reincarnation of his sister? It makes sense especially because she was the one who introduced him to the bl novel, and the fact that the younger brother knew the title and knew the role the MC played in it which contributed to his fear and hatred towards the ML who led his brother to suicide in the original. And maybe thats the brother/sister is heavily protective over the MC's character because they're projecting the memories of their actual brother onto him, unknowing that that's their actual brother.
If this theory is true it'd just mean that the MC actually cussed out the person he's longing for the most, so uh. (￣∇￣")