Lukann
Lukann is a Toa of Earth that had somehow gotten into contact with a werewolf late at night in the woods on his way home from a meetup event with his team.
Though there were reports of werewolf sightings and it was advised not to travel alone, Lukann did anyway...
A werewolf appeared from hiding behind the trees in the woods, Lukann tried to defend himself with his powers and weapons, but the werewolf was too fast and diligent.
Lukann had to be rushed into a medical unit from almost critical wounds, after he had healed over time, he felt and acted strange, having a rather shorter temper than usual and an urge to constantly eat whatever meat he can find.
Every full moon now, Lukann can’t help but change into a werewolf. But since werewolves are feared by most Matoran, he constantly tries to hide so he wouldn’t be taken down.
(still trying to think of his default Toa form atm, I have no idea what mask he wears)