If Glolov decides to be ruthless, he's nothing short of terrifyingly ruthless.
Fierce and menacing, or expressionless and refusing to bow to anyone, pulling a gun at the slightest disagreement—he has none of those classic veteran mercenary traits. Glolov isn't like that at all.
Glolov usually comes across as very gentle, speaking politely to everyone. He's neither intimidating nor overbearing. The only thing that automatically makes him an outsider in any normal crowd is that Glolov always looks at people with a cold, detached stare. That kind of emotionless gaze from Glolov is enough to make anyone feel deeply uncomfortable.
Glolov has killed far too many people. To him, taking a life is no more trouble than tossing a pack of chicken into a grocery cart, and grocery shopping isn't any simpler than ending a life. Within the Satan Mercenary Corps, the only one capable of killing without batting an eye is Glolov.