well it's clear that the hordika is intended to be the bionicle equivalent of a werebeast, I did plan a system where a horidika has three potential stages to go through: fledgling, feral, and peaceful. Fledgling is when they've recently been infected and have three decisions to choose from, finding a cure (which would probably require the GM to either bring in Keetongu or come up with some other deus ex) giving into the beast as a feral which would result in either simply joining the dark side like Vakama or becoming completely beastial. Or they make peace with their animal side. Each of these would have different benifits and drawbacks, fledglings would be farely neutral and pretty close to their original stats as a toa, being a hordika would obviously add traits like primitive weapons, ferocious, and other beast-like things. Feral would have a major increase in strength and proficiency in primitive weapons but tend to drop in intelligence and moral standing, making them insanely powerful but very aggressive and shunned by most societies. Peaceful would be more reserved and intelligent, honing their instincts for things like tracking and controlling their rage for a more percise fighting style. Matoran will still be causious around them but can be swayed by the right attitude to lower their defences. There would be time intervals and situations (determined by the GM) where a fledgling or feral would have to roll a will check so that you don't go on a mad bloodlust and mistake your friends for mahi sandwich, this makes it so that even if the player manages to build a good karma feral there is still a magor risk in playing that kind of character.
After reading through the system of The 3 Vs I thought that would be an appropriate factor that could be used to determine the direction that a hordika would go. Unity is how their team affects them as a hordika, they could provide companionship and strength to help them find peace with the beast inside, or they could be a dark influence, and drive them to become feral. Duty is based on the desire to complete their mission, are they dedicated to their cause so much that they will put aside the animal nature to finish their task? Or are they going to do whatever it takes to get the job done. Or has their motives changed completely and are looking out for themselves only. Destiny well if fate says you turn into a rabid half-rahi or not then that's what happens.
All of these things I leave in your discretion to include or leave out of the final product but I do plan on using this design when I play it.
(This will be my first time GMing anything, wish me luck!)