He doesn't know a lot Alistair. At that time, he has no name and the slave traders are just giving him an alias of silver hair. Alistair doesn't speak too much. He only responds when needed. Even when the slave traders abuse and tortured him, he will never speak a word or let out a sound.
Their situation continued for two years. That was until they landed illegally in the Verdandi Kingdom and they heard an underground auction will happen there and they will be sold to the nobles that are interested in them. Orpheus was one of their highlight products for that night together with Alistair.