Tres is an android and also a member of the AX team. His ultimate weapon is a gun, which explains his codename: Gunslinger. Seeing as how Tres is an android, he has no blood or heart.

If Tres gets orders from Lady Caterina, he follows them because he was programmed to do that. He also supposedly has no emotions whatsoever, but that turns out to be not-so-true. But it is true that whatever emotions he does have rarely show.

He's not very talkative. He usually replies with "Positive" or "Negative". But if he uses full sentences, then he's asking something or explaining something.

According to the official Trinity Blood website, Tres' brain is part human ("made entirely of machines, save for part of his brain"). This suggests that he is somewhat capable of having human feelings, somewhat displayed in an episode in which he was ordered to shoot a little witch girl and did not.

His name, Tres Iqus, is actually Latin for III X, which is his development number