In the comics, Damien Darhk is a baby-faced, genius-level operative of H.I.V.E. who tangled with the Teen Titans. On Arrow, Darhk is a practitioner of the mystic arts , rather than genius technician. He's also a former member of the League of Assassins and a contemporary of Ra's al Ghul (Matt Nable). According to Malcolm Merlyn actor John Barrowman, Damien Darhk's exposure to the Lazarus Pit has different repercussions than what Thea (Willa Holland) or Sara (Caity Lotz) have to deal with. Said Barrowman, "[Malcolm's] not afraid of [the newly resurrected Sara Lance] because, in his mind, he killed her once, he can kill her again. But he doesn’t know what she’s come out of the pit with. Everybody comes out of the pit different. People come out with a bit of every soul that has been put in the pit before. Some parts of those souls take over. Thea’s got a bloodlust. Damien Darhk’s got something else. What will Sara come out with?”
So if you were expecting everyone who emerges from the Lazarus Pit to have bloodlust like Thea, you assumed wrong. Furthermore, the explanation about how the Pit works raises some interesting questions. Were there ever any pure-hearted individuals to bathe in the Pit's restorative waters and if so, is it possible to emerge with better qualities? Or, were there only vile and corrupt men that have used the Pit and thus everyone who steps into its waters is forever tainted?