Spears is my family name. As in one that's passed down to others in the family. [ This makes him pause and frown slightly. Hm, as a reaper he doesn't necessarily have family so...why does he have a last name? He shakes it off, though and continues. ]

William is my first name and the T stands for Thaeton, which is my middle name. Those two are more to differentiate between others, and calling someone by them is more personal than only using their family or full name.