He isn't necessarily evil, even though he definitely looks the part; he doesn't really know what he's doing at any given moment, considering he's a bacterial colony taking a humanoid form. He occasionally has sparks of human intelligence and is completely confused and a little scared when he does, but they don't usually last for more than a few seconds or so. Hecan, however, be affected by the same meteor that created him, and this shifts him into a higher level of intelligence for as long as he's within the meteor's effective range. This colors the veins on his body bright green, as well as his eyes, and generally greenshifts his palette. Now, normally this wouldn't change much- he'd just be poisonous bacteria with a level of intelligence they do not normally have, that's all; just scared and confused like usual. However, the meteor- or rather, the substance within the meteor- has a mind of its own, and uses Nimhe's body as a vessel whenever he happens to be around. This is when he's really evil. Should his body gain enough cohesion to be able to carry the meteor around, the entire universe may be at risk.
I don't feel like formatting this page properly right now, so will finish later.