Okay so theory time 😺
Spoiler!
1. This "younger brother" is actually a childhood friend/classmate the mc doesn't really remember about. Bro got helped by the mc(or bullied but I don't think it's the case..?) and he became obsessed since then. Now that he's an adult (I think..?) he has inherited some business (bro looks rich so) and he has money now. He bribed everyone around mc to make him go insane and seek solace only in him or to approach him step by step (tho it's kinda weird this way)
2. This "younger brother" is actually some spirit/ creature that brainwashed everyone into thinking he's the MC's brother, except the Mc.
2. This "younger brother" is actually some spirit/ creature that brainwashed everyone into thinking he's the MC's brother, except the Mc.
Yep we need more context
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