Been having some trouble with trying to get a character approved, and one of the problems that I am having is my character is a bit of an antagonistic personality needing to eat the livers and hearts of races to recharge mana supplies, this is a high fantasy, high tech school based rp, and I had originally had a shock collar that responded to predatory thoughts, but even after altering it a bit, that idea has been nixed, so I was hoping someone here might have some other options I could consider to keep her from attacking my fellow classmates, cause it might just be writers block, but I'm drawing a blank at the moment -_-.

Well, one thing I know we all hate doing is changing our original idea, but sometimes that works quite well. The fact he has such a violent way to recharge tells most GMs "This guys going to start fights when it's least convenient." I'd change it to that LATER becoming an option, something alot people in your character's race/ family do, and he/her hasn't quite grasped it yet. Your character has other basic ways to recharge initially, they just aren't as effective, or that the character discovers a secret of doing it..... Or is in the cafeteria one day during Liver and onion, and your character accidentally blows up a table upon finding it out. Just delay that part. Just my suggestion. If GM is completely against it, I'd just ask them for suggestions. IF they can't think of anything, they'll probably be easier in letting it pass. If they are absolutely against it, you might have to scrap it all together. Personally, I would have found the shock collar funny enough to keep it.

Normally that would be viable, but unfortunately I was trying to play a traditional kumiho, and they diet subsist on the organs as far as I can see, the GM said I can eat livestock organs for the same effect, but it kinda takes away from the aspect, so I compromised for it being like an IV, filling the need but not being very satisfying. Apparently a collar that increases it's voltage in accordance to antagonistic acts isn't sufficient deterrent to him. This was his reasoning. "1) An crappy electric collar is still not what I would call adequate measure to restrain an inhuman death row inmate" Not sure what he thinks my characters pain threshold is, but slap a collar on Jack the ripper that shock the shit out of him every time he thinks about mauling a prostitute and I bet it'd stop pretty quick. Oh well

Sedatives. Horse tranq will kill him almost dead and leave him nice and placid until he builds up a resistance. Alternatively he's smart enough for self control like some killer from Criminal Minds. At least up until the point someone knows they got a serial killer on hand and summons some higher-level law enforcement with all the tools. Beyond that: why is this person not isolated and in a padded cell? Is he Deathmold?

Keep the idea of him needing to consume livers and spleens to charge mana, and get rid of the collar, it is cheesy imo, your character is badass, slapping a collar there hurts your character's image. Here is a suggestion that might impress that GM, Have your character develop a weakness to human blood, so even though he needs to feed on liver and spleens, the sight of blood weakens him and therefore can put him in a vulnerable situation. This should automatically limit the risk of your character going beserk and tearing up students for livers, since that much blood will make your character a class A wuss.

I had a similar character for an RP ages ago. (Radiation poisoning and needed blood transfusions in order to live) This character would basically knock out the person and steal their blood like a vamp, but through the use of an IV needle. This left the option for if I wanted to kill the character in question or just let them live whereas your trait seems to rely on death. Another option is that over time you can add disadvantages like blood poisoning or many other medical conditions that may weaken your character. Let's say that they take the liver of someone dying of cancer. That liver may replenish mana but it could also create a very sick individual. It's similar to what @oakman mentioned about the sight of blood, but you can play that as Joker like card to make your character physically weak. And yeah, ditch the shock collar. It just raises questions like, "Why has he got a shock collar?", "Why not get it removed?", "What happens when the batteries run dry?" or "Is a little pain worse than dying?". You've got an awesome skill that on it's own you can play with quite well as it's able to mix health, power, and mana into one bundle that has to be managed. Generally the weaker you can make your character the more you can develop their personality and nature.