He and is family lived in the wilds, making their living as guides and foragers. The family followed the religious beliefs of Avandra with Thaddeus being gifted with magical talents. When the family was attacked by gnolls, Thaddeus was the only one to escape by means of those magical talents. He then used those talents to lead monsters and adventurers to the gnolls under the cover of a mystical entity in the woods until their complete extermination.
Over this time period, his sense of justice and morality began to balance between chaotic and lawful. Having avenged his family, he decided to head off into the world to hone his skills and take up the cause of the weak and oppressed.
Thaddeus is friendly by nature and loves a good joke. During his time in the forests, he often found himself in the company of faerie dragons, joining them in their jokes on passersby.