There is a whole lot to say about Caspar Lawrence, but much of it is history. There is his link to the Shadow Lords, a link known to very few. A complicated history, to say the least.
Then there is his ability to cast sorcery. Not quite a Mage, and not quite a normal human either. His link to the mystical arts stems from his unnatural blood, and it is a gift that he uses fully and freely.
Caspar may have a complicated history with his Tribe, but he does help them when they require it. There is a reason why he became a Private Investigator after all. It has so many uses and it speaks to his personality so very well.
Part of the reason for why he is, at this point, a rather accomplished Sorcerer, is his Tribe; the Shadow Lords. It was not so much that he resented the fact that he was a mere 'Kinfolk' to the True Born brothers and sisters of his tribe. It was more the fact of how they treated him, how they seemed to Lord (pun intended) it over him. At each turn, he was the mere Kinfolk and there was all there was to it. So he always knew he wanted to do more. Knew he could be more.
The turning point in his life came when he was introduced to the power of Sorcery. To the primal energies that lay untapped within him. With the right knowledge, the right books studied, he could and eventually he did learn how to tap into those energies. After that, it was all just a matter of reading more. Finding the right books and learning what it all meant. No longer would he just be Caspar, the Kinfolk to a Tribe of arrogant men and women. Now, he could create his own destiny.