Zeros first appeared in Slayers Next, making on and off appearences...we don't actually learn much about him until Slayers Try.

Zeros is the mysterious, dark character in Slayers who hides behind shadows.... although when he isn't hiding away, he enjoys leaving clues to unsolved questions that only lead to trouble. He's very secretive about his life, and tells only what he wants and when he wants...usually, he'll just answer "Sore wa himitsu desu!" just to tease. Besides the fact that he's the most destructive life form in the universe, he seems to have a VERY giggly personality. (His giddieness can become annoying at times...) Hmm... an interesting example of his "silliness" is in a Slayers Next episode when the group had to travel through a town inhabited by only women, and Zeros had to dress in drag, he certainly got into character..... just take a listen!

Zeros also has a bad streak.... he lives to see others in pain, and doesn't really care whether he's in pain or not. He's almost invincible to most attacks..

Superficial as it may seem, I believe that the fact that almost NO info. is common on Zeros is a major cause for his seeming lack of popularity.