Of course they are done for simple sadism. Guns exists to kill, and inflict pain, and the motivations behind those actions matters little. Those who kill in war and those who kill in peace are still taking lives, are still changing the world one person at a time, changing personal history and sometimes entire countries, sometimes the entire world. But Guns is not sin, because sin at least recognizes its own guilt, and 'evil' gives his malice too much intention. He is a machine of a god; he can only be evil if death and pain are.
The transition is gentler this time, as they fade from one space to another, appearing outside the coffee shop again. He lets go of Fetish's hands to suck his fingertips into his mouth, one by one. "Well," he muses, "I think that's enough for one night." There's always tomorrow.