You give me a lot to think about. And perhaps a rehabilitating bad guy would be a better idea. I'm just concerned that I lack the manpower to sufficiently develop two drastically different routes. Because I definitely want one of them to be purely evil. As far as why I chose it to be a vampire, I want body possession to be a big part of the game, not mind control. Which although this ability will have it's limitations, it will be utilized several times throughout the game. Also, I'd like to give the game a little bit of a gothic horror flavour and vampires fit the bill perfectly. So to answer one of your questions, no, it will definitely not be a comedy. I want it to be tonally much more of a suspense drama with a little action sprinkled in.
You really need at least a basic story pitch to achieve anything coherent. Currently you have gameplay concepts and have picked a flavor. But you need something like this:
Context story:
(MC is Wolfgang, since I have a thing for calling them all Wolfgang, and using "MC" doesn't feel right.)
Wolfgang is a vampire. He was part of a very prominent vampire clan. He was somewhat of an outsider, tho. Something with his turning went wrong. He kept some semblance of empathy, unlike his brethren. but the beast inside him was still awaken. The beast feeds on domination and control of others. The emphatic part - on bringing happiness and helping. You can imagine how that problem, combined with the mystical powers vampires have made Wolfgang a full-blown schizophreniac. He sometimes has arguments whit both the beast and the human in him. The clan kind of kept him at the periphery, since he was useful - even if only by the fact, that he could walk around at day, but didn't like him much.
Well, the clan is gone now. The Hunters came and the clan lost. Gladly it was a Pyrrhic victory for the Hunters, so Wolfgang managed to escape. He was actually what teared trough the Hunters lines with ease, since his inner human made him immune to most of the weapons the Hunters used. But now he is hunted. By the Hunters who see him as a real threat to their order if he ever decides to take revenge. By the other clans, who blame his existence for the spike in Hunter activity. And by the Company - a shady organization that wants to capture him. For some reason.
So Wolfgang moved. Bought a mansion in a small town on the Northern East Coast. Tried to sort it out. Have you ever heard of a vampire suffering from nightmares? Yeah, he is the firs one. But one day he gets word - the Hunters are actively searching for him. Now, his clan got duped by the Hunters infiltrating the part of the city they lived in. Not happening again. Both sides are in agreement - the locals must like him and or serve him if he is to survive. But where to start? How about that sweet little girl, that walks dogs every morning next to the house.
Now one can go on about making a game with a story. And can attach several mechanics to the game, based on the story.
Obviously there will be domination and affection path for NPCs. Affection leads to loyal followers (well, with some encouragement... you are a vampire after all, but it's for their own good). Domination leads to thralls. Who doesn't love keeping slaves to command and abuse? Oh, well, vampires do!
Wolfgang will have to do some bad shit now and than to satisfy the inner beast. And some good shit to satisfy the inner human. Or try and keep them under control, but that would waste resources of some kind (probably blood, since having enough blood to drink is kind of important, and blood can be a stamina-type resource).
He will have to try and not stir way too much shit, or one of the organizations will find him. He can fight them if they do, but that will take a lot of resources. So let's say there is a stat "Activity" - 0-30 no problem. 30-60 - Company attack. 60-90 vampire attack. Drops slowly with time.
At day X the Order will start infiltrating the town. A new cashier here. A new cop. A new family moving in. A new business wanting to open doors. Did you control the important marks? The mayor, the police chief, the bank CEO, the priest, the neighborhood watch chick? Did you go for dominant path? Good, they stop the hunters. But a lot of them die. Not that you care - at this point your inner human is just an echo in some of your dreams. Did you help and protect them? Cool, they will stop the hunters and you can spend resources to save them. You inner Beast is tamed now. You control him and keep him in check.
Oh, and by the way if you ignore your beast too much it will overtake you if you don't have the power (i.e. blood) to stop it. Fuck someone. Dominate somebody. Kill shit. You are a vampire. Even friendly vampires aren't nice. And loosing it in the middle of the day and slaughtering a bunch of people is not the best way to hide.
I'm not saying "you should do it like that"! I'm just pointing out how even a concept I spent less than 30 minutes on can guide the game from the start to the finish and help you figure out the macro picture. Than you can keep that in mind working on the micro stuff. Characters, specific mechanics.