Evil serial killer is too likeable?

One of my characters is a serial killer. He probably wouldn't be if he didn't have to kill people to live (aka if it didn't benefit him), but he has no remorse, enjoys it to some degree, and has zero respect for his victims. Actually, he doesn't have much respect for anyone other than his friends and even then, he's pretty mean. The only thing that keeps me from saying he's a sociopath is that he genuinely does care about his friends and he has a soft spot for other monsters.
Now, I've got this idea that one of his victims fights back, survives, and becomes a monster like him. As she learns to adapt, she comes to forgive him, he takes her in and helps her out, and becomes sort of like father figure to her. (The act of fighting back would have endeared her to him and he has a soft spot for other monsters.)
Would this make him too likeable?

Three more quick questions if that's ok:
1. I have a house with eleven monsters in it and more characters that aren't in the house. Should I get rid of the mermaid? She doesn't really do much other than be the resident girly monster and I'd like to keep the alp (who also doesn't do much yet).
2. Would a romantic relationship between a zombie (undead) and a frankenstein monster (undead) gross you out? How about a warlock (living) and a bride of frankenstein (undead)?
3. How would you suggest making a female, blonde vampire hunter not be like Buffy? Aside from the fact that she gradually turns evil/trickster.

I'd say that, as long as your MC keeps killing people and being a sociopath then you should be ok. If he starts wanting to keep bunnies and drink cocoa then you're in trouble.

Eleven sounds like a lot. I would thin the herd.

The romances you list make me think (for no real reason) of the munsters. That is, comedic rather than anything else. It's tricky territory you're in - tread carefully.

Easiest way for someone to not be Buffy is to not wisecrack. And not be a cheerleader. And not call her stake "Mr Pointy".

Aaahh, Stockholm Syndrome, here we come! Don't worry, as long as he stays a monster you'll be okay.

Personally, I think that makes the character more interesting. In reality, "bad guys" are not 100% evil. They do experience feelings. After all, as many people as they kill, they are still human. As a complete Buffy nerd, I shall make a reference. In the third season of the show, the main villain (The Mayor) actually forms a very sweet, father daughter relationship with Faith, another slayer who betrayed Buffy and her friends. You kind of felt bad for him when Faith went into a coma near the end of the season because he clearly did love her, but you still completely wanted Buffy to win in the end. I honestly think the best villains are the conflicted villains with actual feelings of some sort.

As for the Buffy question, I guess you could make her a tad "harder" and less girly. In one episode (Again, total Buffy nerd here. I have a problem), they showed an alternate universe, and Buffy was extremely unBuffy like. She was a tad more blunt, and less trustworthy. Definitely a bit of a loner. You could do something like that. Make her a "bad girl" or something. The thing about Buffy: she still liked girly things like clothes and boys, was very wisecracking, and genuinely tried to be good (she would never kill a human being, no matter how bad he was). She also many times resented being a slayer, and didn't always take it very seriously (hence the wisecracking). Just try to step away from that a bit.

Nah it's not stockholm so much as she realizes that she does the exact same thing to people. She feels she can't really judge him when she is almost as bad. That and his house is the go-to house for monsters who need help adjusting or a place to stay. I don't think she'll live with them (there are already eleven), but she will drop by.
Hehe I'm a Joss Whedon fan, but only recently got into Buffy. Nah, she's not too girly or a cheerleader, but she does angst a fair bit about being manipulated into a vampire slayer.

Thanks everyone for your help!

Just don't make your villains easier to cheer for than your heroes. I read a vampire series once where I really liked the vampires -- they were so much more complex and more likable than the slayers (one of them was a drunken gambler, the second was an emotionally repressed woman who couldn't admit to herself for ages that she was into her partner) whereas the vampires had actual 'good' motivations. The slayers were in it for the money. Every time one of the vampires died I'd start shouting at the book. Eventually I stopped reading it, after my favorite vampire helped out one of the slayers (saved one of their lives!) and they killed him for it.

Other than in that kind of scenario, I don't actually mind a likeable villain.

As for the Buffy thing -- Buffy does go kinda off the rails, so I'd be a little bit careful about that, if that's how you're going to make her seem different. I wouldn't worry about it too much though. Focus on making your character seem like a person, rather than making her not seem like Buffy. (I recently had the same problem but I had to make my character seem different to Dexter)

My ten cents :)

The thing that jumps out at me here is this. People are people, good or bad, we are the same. Just because the serial killer is doing evil things that does not mean that 100 percent of what they do is evil. They can do nice things to. Bad guys can be good guys. There are many examples of this.

Dexter is the best example from fiction, he murders tons and tons of people but we love him and we want him to succeed. We don't want him to get caught. It is because Dexter does murder, but he has a set of morals that only allows him to murder those that he has proven to be murderers themselves.

Ted Bundy is a good example from real life. This guy killed many people in truly horrific ways, but was extremely charming and good looking that people refused to believe it at first, and many didn't care and women were lining up to be with him in prison. He is was very well liked, and a very evil serial killer.

Life isn't black and white, everything is shades of grey. Good guys have a lot of the same qualities of bad guys because they are both humans, and the only thing that separates good from bad is just a series of choices and situations.

If a good person is put in a position where they must kill in order to save someone else, they have committed murder but for a reason that was good to them. Society will label them a murderer and by extension a bad person, but they might be the best person ever but now they are labeled. After that the murderer might be in prison with other bad people and the desperation of the situation might lead that good person down a path that gets more and more dark.

As for the 11 monsters, damn yo, that is a lot of monsters. My advice would be to simplify it down. The best monster movies/books have only had 1 monster as the threat. Dracula, the wolfman, the creature from the black lagoon, frankenstein. Zombie's have many many monsters but they are essentially the same monster so it's more like it is one monster that keeps coming back again and again. When you start bringing in everything you can think of together, you get too many spices in the soup. It starts to taste weird.

Buffy is Buffy because she has certain characteristics, headstrong, tough, snarky, and sarcastic. If you want to differentiate your character from her, make yours the yin to Buffy's yang. Make yours a sensitive, reluctant hero. She doesn't want to be the one to save the world from vampires but she knows that she has to, so when she has to step in and stake the fangers she may feel bad about killing. And if she is feeling bad about killing them, this would lead her to being remorseful or make her harden and become more detached from the world.

Just some input.
Casey

I mean no attack.

I was just simply trying to say, that people have many sides. Evil and likeable can be two of the sides. I wouldn't worry about a "bad guy" being too likeable. I would worry if my antagonist is becoming the character we care about more. If you are worried about the Draco in leather pants idiom, make the character physically hideous. When someone is attractive it's easy to overlook flaws.

Also I only mention the famous monster stories, for the fact that they are examples of the monster genre that have been successful, iconic stories. I don't think they would have worked as well if there would have been a bunch of other cool monsters in there stealing the spotlight.