Oliver Queen was more than a bit free with his arrows in his show’s first season. The body count was amazingly high on Arrow as he tried to stop the Undertaking. With his best friend dying, Oliver promises not to kill as freely as he did before. But murder seems to be a hard habit to break — the insane immortal Ra’s Al Ghul, the mystical Damien Darhk — but Oliver killed when it was the only option. But the Flash, good-natured, dependable Barry Allen, is more sinister than he seems. Pay attention and you’ll see that he drops bodies left and right, smiling all the way.
Back in the pilot episode, Barry tells Clyde Mardon that he’s not a killer. Which is true until he faces off against Multiplex – in the very next episode. After Barry super-speeds him into a steel support (which somehow doesn’t kill him), he then dangles him out of a window. Maybe Multiplex did grapple himself out of Barry’s grip but suddenly the fastest man alive can’t operate stairs? Only a few episodes later, he punches Girder at the speed of sound. When Tony is talking with Iris, he’s all pink and squishy. If Woodward hadn’t been able to get hard enough in time, we wouldn’t be talking a knock-out punch. We’d be talking dropping melons off buildings. Splatter would have gone everywhere. In Rogue Time, he casually points a gun at Snart’s baby sister. Grodd Lives, he tries to murder an innocent gorilla who definitely cannot turn to metal to protect himself. Rogue Air, he gathers together mass murderer Oliver Queen (currently serving with the League of Assassins), Firestorm (who can only blow stuff up and fly at this point) and proceeds to brutally attack what amounts to a marooned time-traveller trying to get back home. Why doesn’t he just lock the door? We all know the Flash can’t escape the Pipeline so just put one of the boxes in front of the door and wait patiently. Brace yourself, we’re still in the first season.
In this season, we’re introduced to the Multiverse. In literally the first episode, Barry and his band of merry murderers conspire to throw a man into a nuclear reactor. Next episode, he hits a guy with a bolt of lightning, shattering the Sand Demon into fragments. Going three for three, the Flash just stands idly by as Snart junior kills daddy (who admittedly had it coming). Fourth in a row, he burns a man’s brain apart. Episode five, he watches Zoom (as Jay) and Wells punch each other a few times before stepping in. The Scarlet Speedster evens smiles before he breaks up the fight. I could probably list something for every episode but I think you get the picture by now. Allen isn’t the moral guy we thought he was. To pick a few choice moments from the rest of the season, he attacks Grodd (again), electrocutes a man-shark, breaks the time barrier to consort with the Reverse-Flash, ages Griffin to death and casually summons Time Wraiths to kill Zoom (at the expense of himself – kinda).
Oliver deals with his kills by having a bleak outlook on life and generally hating himself. Over in Central City, the sun is shining, the birds are singing and smiling Barry Allen has another body at his feet. Plastique dies? Blame General Eiling. Eddie is kidnapped and held – unharmed – for a few days? Clearly Eobard is insane. Sand Demon shattered into pieces? What a hero the Flash is!
Psychopaths feel no genuine attachment to others. To them, people are merely pawns to be used to further their own goals. They also feel no guilt for their actions, regardless of how much they actually hurt others. They hold down steady, normal jobs and can even have families or seemingly-loving relationships with partners. So imagine your mother was viciously murdered. And now, you have the murderer locked up in an inescapable cell. Well, Barry did. At the expense of Cisco’s health, Eobard could have stayed locked up indefinitely. But it would be more beneficial if Cisco was at the top of his game so Barry gives Thawne a helping hand on the road home. Another key trait of psychopaths is that they meticulously plan out any criminal enterprise to avoid any risk to themselves and have plans for every eventuality. Almost like Barry and Team Flash do every time they plot a kill capture.
With several accounts of murder, a couple of animal cruelty and a job where he will process all the evidence, Barry Allen is a scheming psychopath who could kill people before they can blink. Knowing full well that changing history has dramatic effects on the present/future, we last saw him kickstarting what will be CW’s Flashpoint. Congratulations, you’ve just erased an entire timeline, effectively murdering everyone in it. And don’t forget how the DC Flashpoint turned out with the Amazon/Atlantis war. Barry started World War Three and the final days of humanity. What a hero.