Zechs' look back was just polite enough not to be a stare, per se - but it was also blank, and largely inscrutable.

Not military, not private militia. Options: Spy. Highly skilled member of an organized criminal organization. Terrorist. Assassin. A very blunt liar about being either part of a military organization or a private militia.

"I doubt our pasts matter here." Zechs told him. So, he didn't really care what Rieper's background was. "But it's good to see there are other people with considerable skill, no matter what situation we're thrown into."