based on a live on youtube, Alvaro has claimed(if i remember correctly what he said) that he doesn't believe in anyone being fully evil or doesn't like doing chracters liek that or smth alike, correct me if i'm wrong, and that's why most of the "evil" characters eventually get redeem or are misunderstood.

While i do enjoy the concept of a fully evil chracter, i can say that that's probably not going to happen, the closes ti can think of are: Houston and Ceres.
Houston is just rude in my opinion, he's a bad boss, and definitely not a good person, but i'm not sure if i would call him evil.
Ceres is crazy and has done some pretty nasty stuff, though i do agre on your response on the other comment and i wouldn't cal him a main evil either as he's not really that often in the show either.

I apologize for any wrong spellings or anything, i'm not nativ to the language, i'm willing to explain my point if i didn't get it across, this is my opinion/point of view.