my theory is that the chuuni best friend was the one who wrote the webtoon, and he modelled the protagonist after the mc (similar willingness to help others and natural rizz), then na ri after park jung ah since he would have probably been aware of jung ah's affection for na kang lim with the three being close so maybe her darker, twisted side too. despite being in the apc club with the rest, the main girls often forget about his existence entirely as a laugh so if he's deliberately manipulating the cognition of the characters he wrote in order to spectate na kang lim's story in a side character position that would make sense. we can't definitively prove he isn't aware of the webtoon events since he could have just lied in the opening chapters about not knowing about the existence of the webtoon, and although his chuunibyou is often the butt of the joke, him actually being as powerful as he makes himself out to be would be ironic
i hope if this is the case and his position as author is revealed that he still continues to be a bro to the mc. while he has gone through hell with the resets and experienced countless deaths and failed tragic loops he has changed, grown and improved himself through the trials and is also able to socialise with others more unlike the loner he was before. if i were to write this plotline i would make it so him writing the protagonist as this perfect, charismatic and handsome guy is because he greatly admires na kang lim as a person, and he is not revealed as a twist villain or something. we also know that na kang lim was a massive fan of the series, so that could further the bond between them