He is a fun character to write because he is so hateful and genuinely dislikes everyone but that also makes him a character that's basically unplayable in most company because he is so hateful and genuinely dislikes everyone. It's not like he's rude with people or anything, he is actually very outwardly polite, but he is very uncooperative and unwilling to entertain people, and yeah, it doesn't really work in free for all setting.
Being such a hater is mostly true trauma, though. Meredith is a... complicated case of being a life-long social pariah, raised by a parent who was both neglectful and overprotective. He didn't have friends growing up, and he was considered a weirdo by his peers, who would often bully him during the times he was actually allowed to spend time with other kids. Things didn't become better when he grew into a teenager, and not when he grew into a young adult.
When he was raised one of the Forsaken, he couldn't find kinship with them either, and the living... well. being undead isn't exactly how you become popular, right, okay. Undead are distrusted and disliked by many. Most? In any case, what I'm trying to say is that Meredith hates everyone because everyone hated him first. Being disliked and distrusted for his whole life has festered into deep bitterness. He thinks other people are stupid and worthless -- and since he is Very Depressed, he also thinks he is stupid and worthless. It's complicated, you might not get it if you haven't struggled with feelings like that (and I guess you are lucky if you haven't). If you try to be genuine and kind towards him, he will regard you with suspicion. People aren't kind to him, so you must have ulterior motives, and he will not trust you. He doesn't respect anyone, and doesn't trust anyone either.
Deep inside I do think he would like to be more liked. It's very exhausting, existing the way he does, but at the same time, it might just be impossible at this point. Then again, he has some people he tolerates, and in some cases... well, in one case, even likes, so maybe not all is lost. And if everything fails, there's cats and books.
