Luke is a half-blood. He is shown to have a good relationship (FRIENDSHIP. HE IS ALSO VERY GAY) with Alex and many other of his fellow half-bloods. He is supposed to be seventeen in the first book.
Luke is very badass. Deal with it.
He and Deacon are in a very homosexual relationship. Deacon is bisexual, by the way. Just thought you should know. They're my OTP.