When the MC becomes evil in a sci-fi/fantasy, it's pretty easy to have them turn around and start blasting away at everything they felt wronged them; going on giant killing sprees while ranting about how the world treated them like shit, so they're giving the world exactly what it deserves. The problem is, when the setting is in our world, the MC can't exactly do that. Case in point: in my General Mysteries set in modern times, the MC (Kevin McKinley) discovers the last thing about himself that he ever wanted: he enjoys seeing those he feels are criminals at his mercy, he enjoys the power he has on them. Think Frank Castle from The Punisher, only Kevin isn't going around murdering everyone left, right, and center. This is more of a deconstruction of The Punisher if anything else. The idea is that Kevin McKinley discovers this side of himself and slowly but surely begins to descend deeper and deeper into that side until he realizes he's gone too far and tries to redeem himself. Now unlike Frank Castle, Kevin doesn't have access to every single military-grade weaponry to unleash hell. At best, his weapons are a knife and a pistol. That's it. Not exactly I'm-The-Punisher-All-Shall-Fear-Me style. He's a college-aged student living with his aunt, uncle, and middle-school aged cousin. So my question is, how do I realistically go about having him go from a generally kind-hearted individual to becoming a vigilante who takes pleasure in causing his enemies emotional distress (he doesn't kill them) without blatantly ripping off of The Punisher? Thoughts?