Drunken Guard

A DC 14 Streetwise check is enough to recognize Grau as the former Watch Sergeant. No skill checks are necessary to rescue Grau from his life of constant inebriation. If the PCs decide to sober him up, or escort him back to the guard, Grau isn't in much of a position to do anything about it. Deciding to ignore him is the only real way they can "fail" this encounter.