Seamus is 5'2" tall and just over a hundred pounds. His hair is a bright, fiery red and grows wild so he has to keep it cut short or medium so it doesn't go everywhere. His eyes are a deep, emerald green that have a bit of a wild glint to them. He doesn't seem overly athletic at first glance but he has a wiry look to him when you look closer. There's a sort of animal-like grace to the way he moves.

When not in his school clothes, he always wears thick heavy jeans and long-sleeve hoodies or turtlenecks. Most of them have the look of hand-me-downs.