Alei is a wandering salesman and, despite having the same surname as Aelix and Emil, is a very distant relative of theirs. In fact, they aren't related at all by blood, only by surname.

Alei was a mage, but he gathered a hoard of useless items while trying to make himself immortal. Eventually he was able to grasp the formula that allowed him to stop aging. Now that time has no grasp on him? He's selling all his useless stuff, or at least trying to. Do your best, salesman!

Out of canon, Alei used to be Aelix before Aelix was redesigned. He's named after the cannibal fish, Alepisaurus ferox.