Ciel

Personality
Ciel is incredibly shy and afraid of interactions with others, standing in a crowd of people wouldn't work for him. He is too anxious to talk with strangers around. He never openly shows his emotions and tries to keep everything to himself. Only if he's around his brother or sometimes if he's alone with the little dragon, he will let go of the wall around him and start smiling or talking.

Story
Ciel and his brother were born into a rather normal family but thanks to extrernal problems (guild laws, territory wars and such) the children were seperated from their parents. (not sure whether they're dead or only far away) This caused a trauma in Ciel and was probably what initiated his extreme social anxiety. His brother took care of him from this point on, working as a mercenary for various guilds, until he met Vanir. Ciel didn't really meet Vanir at first, it was another job, so he stayed home where he was alone. After a while though the job really seemed to affect his brother. Vanir seemed to be more than just a job at this point. Which is where the two of them met. It still took one hell of a long time to get Ciel to let down his guard around Vanir. Slowly but surely he made progress though.

The dragon: Ciel met him a while after the siblings got seperated from their parents. It was while traveling into another region. He's always had a good relationship with animals. They didn't talk so that was good. But the dragon stayed around way longer than any other animal. And Ciel got a lot more attached than usual. So eventually he made a contract with the dragon who then became his familiar.