Atreus is a massive man, towering over everyone around him, at 8" of height, and weighting about 540 pounds. But he's all muscle.
When they were little, he and Democritus, who is his brother, used to be a bit shunned by the other kids. Democritus because of his Gift, and Atreus because of his Magical Air. But he always looked after his younger brother, being the most burly one. And even more so when his growth spurt started and he easily towered over everyone.

When Democritus was taken to his apprenticeship, They tested him as well, and when it was clear he doesn't have the Gift, they taught him the use of weapons, so he can serve as a guard for his brother.