Does Dex’s devolvement into a grinning mass murderer in someone else’s superhero outfit scan, as far as psychological motivation goes? Well, no and, uh, no. A hard “no” in the sense that, as witnessed last episode, his backstory and history of mental illness is kind of sketched-in and scattershot and hard to swallow. You can’t methodically pick apart a character who was never a cohesive whole to begin with, no matter how hard Daredevil showrunner Erik Oleson, writer Dylan Gallagher, director Stephen Surjik, and actors Vincent D’Onofrio and Wilson (!) Bethel work to prove otherwise.
But also a soft “no,” in the sense that no human being in the history of human beings has everdevolved into a grinning mass murderer in someone else’s superhero outfit, because there are no superheroes. There are also no supervillains whose unerring aim and throwing capacity enable him to turn any household object into a lethal weapon, whether they’re dressed up as Daredevil or have their own snazzy black-and-white costume to do their killings in.
The point I’m trying to make here is that this season, Daredevil decided it needed Bullseye, so Daredevil created Bullseye. It could have gone the route of both the comics and the original Ben Affleck/Colin Farrell movie version and had the Kingpin hire an out-of-town hitter with a badass reputation, but it tried to grow one organically from within, tying his origin directly to both the protagonist and the antagonist of the show. Is there any way to do that in a wholly realistic manner? Not when your show is Blind Radar Ninja, Attorney-at-Law there isn’t.
So, y’know, have a little fun with it! Do some creepy voices and camerawork, put some baggy eyes and flopsweat on your handsome new actor, give your main heavy a chance to play master manipulator and guide a new killer to follow in his footsteps a la Hannibal Lecter. Kinda churlish to complain that the end result isn’t in the DSM, no?