Once upon a time there is a kid born into a rich family. He is immediately kicked out and left to fend for himself after his "father" finds out that his wife actually had an affair with an elf. He somehow gets put into the care of a group of traveling merchants who take care of him but also use him as their personal slave. At a certain age around (somewhere around 15,16) he discovers what him being a halfbreed means: Humans can only use X type of magic and elves can only use Y type of magic. By being a halfbreed he can use both making him very valuable for certain people. After the merchants find out he is sold to a guild or something where he rises in rank and power (he is still a slave though so he is limited in how far he can go). As he grows older near his (18,19,etc) birthday he is then admitted to the Arena, a basic gladiator style arena. Through the arena he starts to gain his freedom. Later through impressing a king in a far off country that came to watch some fights, he is then asked by the king to come with him and help him build his city into an empire.