https://www.mangago.me/read-manga/yang_il_woo_and_i/ VERY much yes. Mc’s dad heavily abused him in the past (and this is continuously referenced throughout the story) AND he currently has a toxic relationship with someone.
https://www.mangago.me/read-manga/the_mountain_branches_dream_of_goblins/ Kind of…? I wouldn’t say he’s an extra black flag character per se, but he is manipulating the Mc (this is only revealed later on in the story tho)
https://www.mangago.me/read-manga/a_gloomy_delusion/ Sort of yes. The torment hasn’t quite started yet from my memory.
https://www.mangago.me/read-manga/sahan/ Yes, in the past. In the present, I wouldn’t say this character ABUSES the mc— hell, he barely even DOES anything. However, he’s toxic in his own way and does something rlly important in the season finale
https://www.mangago.me/read-manga/the_night_is_soft/ Yes, in the past. Mc’s abusive dad.
https://www.mangago.me/read-manga/nerd_project/ Kind of, but it never went to an extreme extent. Mc is being harassed by someone akin to a boss (it’s hard to explain cause spoilers)
https://www.mangago.me/read-manga/mr_do_hoon_of_the_rose_mansion/ Yes, in the past and some of the present. Mc’s mentally, emotionally and neglectfuly abusive dad.
https://www.mangago.me/read-manga/guiding_hazard/ Yes, in the past and in a bit of the present. HORRIBLE ex
https://www.mangago.me/read-manga/love_sick_dog/ Yes, in the past and the present. Kind of like an ex but not really but they weren’t quite friends and yeah

Does anyone have recs with an extra black flag character that torments mc/ harms Mc or manipulating him. NOT THE ML, an extra character other than the ML.