**not disagreeing with you specifically**
You’re right abt locking MC up, but the MC has feelings for him, so we can’t assume that (as of rn). Being possessive of your SO is completely normal bc that’s your lover. Obviously there’s a fine line being “that’s my lover” and “touch them and you’re dead”. And as of right now, Shin is perfectly fine. Granted, someone did touch MC and they did (nearly) died, his reasoning to do what he did shouldn’t be a strike to make him a yellow flag. This novel is omega verse, so a lot of things are different compared reality and other non-omega verse novels(?)/series/books I’ve read; but comparing it all, Shin shouldn’t be a yellow flag due to showing a little possessiveness. I mean, his lover was literally in danger and he had the power to stop that from happening. Outside of that, he hasn’t done anything to MC to make him uncomfortable or afraid.
Not ppl actually saying that SHIN is a red flag bc WHERE IS THE RED?! All I see is green. Shin is one of the good ones yall. If yall think beating up your significant other’s rapist/bully/kidnapper/etc. to (near) death is a red flag, then 1) you’re definitely single and are not ready to mingle. 2) yall got your morals crooked, and 3) re-read the whole thing bc I know yall didn’t actually understand a single thing