He always reminded Mary of a family dog.
It wasn't just the sharp features and the freakish loyalty. Marshall was a Husky: sleek and gorgeous and steady. The perfect addition to any family- loping along beside you and not minding when you invaded his space, as long as you kept him fed- until someone threatened his family and boom! Wasting no movements, he'd have you up against a wall, teeth bared in a feral sneer, ready for blood and you think "Holy Fuck. This dog comes from wolves."
It was the same for Marshall. He wasn't aggressive like she was, but he had this deep undercurrent of violence that was sudden and smooth and intrinsically a part of him. It wasn't hard to imagine that not long ago his people had been warriors, Franks of Visigoths or whatever the fuck.
Mary liked knowing that about her partner; knowing something that other people didn't know, didn't see. Outsiders thought he was good at his job because he was dedicated and diligent, and sure, that was part of it, but Marshall? He was good because he was feral, instinctive.
Probably it was part of what made them good partners, that they both understood violence; that they understood that justice and blood sometimes had to coexist, but Mary didn't really think about that.
Mostly she just grinned wryly and enjoyed the show: Marshall Mann. U.S. Marshall. Badass.
"People sleep peaceably in their beds at night only because rough men stand ready to do violence on their behalf." – George Orwell