I have finished making my backstory:
[spoiler]
His father got killed when Dareidor was very young since he stole some food from a store and got caught. His mother got killed of some guards that wanted to have fun. Dareidor was underestimated a lot when he grew up in his school, because of his race, and because of his parents, and was bullied with a lot, so he spent a lot of time on learning to show that he was not inferior to the others, but superior. After a while, he started to get crazy. He wanted to be superior to the other kids in all possible ways.
So he found a Factotum master to teach him, but his master was also secretly a Death Knight. His master tricked him slow and steady into being evil. After a while Dareidor realized what was happening, and surprisingly, he liked it. And as his master always said: "Evil wins, because Good is stupid". But due to his superior intellect, after a while, Dareidor felt superior even to his new master, so he decided to find someone that he actually could learn something from, so he left his master to go on new adventures.
Often when he got to cities, he got bullyed by people because of his race, but those that did that were captured by him, bound in ropes, and then first he proved himself to be much smarter (and if there was something they knew that he didn't, he had even learned something new), then he tortured them a while, before he killed them. This happened in many towns before he found the Duke of Logic, Caim and he was willing to take him to Dis. Dareidor wanted to go to Dis because of that there hopefully was someone in the city that was at least almost as smart as him.
He liked being in Dis, and he used some time on crafting, and he learned to throw Shurikens very effectively with his tail. He did also show everyone that Beguilers aren't stupid, but instead smarter than regular humanoids. He liked the way Dispater was, and started to worship him. The thing he has missed most in Dis, though, is toruring people. But he does still think that it is worth it, and he will do almost anything Dispater says to him. He does also talk a lot, and likes to learn new stuff in any possible subject. He hasn't got any last name that he can remember, and even if he had, he would prefer to hold it a secret.
[/spoiler]
And I am almost done with making him (has 6.4kgp left, and could need a weapon, and has an open spell slot, but not much more than that...