WARNING: The following article contains major spoilers for this week's episode of Arrow, "Crisis On Earth-X, Part 2," which premiered Monday on The CW.

The good news for Arrow fans is that Tommy Merlyn is back. The bad news is that he's a Nazi. But wait, it gets worse.

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More than four years after Oliver Queen's best friend died in Arrow's Season 1 finale while rescuing Laurel Lance in the aftermath of an earthquake, he returned this week -- alive if not exactly well -- in "Crisis On Earth-X, Part 2," where he was revealed to be the Prometheus from the parallel world where the Nazis won World War II.

Captured by the Arrowverse heroes in the fight that followed the crashing of Barry and Iris' wedding by invaders from Earth-X, Prometheus was imprisoned at S.T.A.R. Labs, where he brooded in silence, until the opening moments of Arrow. Unmasked, the identity of the smiling villain, portrayed once again by Colin Donnell, takes Oliver completely by surprise.

The Tommy of Earth-X is a sympathetic figure, at least initially, admitting that he'd "almost prefer" being dead, like his Arrowverse counterpart, to living on his world. "I was born into the Reich," he explains. "The whole world is the Fatherland. We don't have elementary schools and summer camps. We have ... youth groups, military training. We all grow up without choice."

How can Oliver, and the audience, not feel for this Tommy, an obvious product of his upbringing? See, he doesn't want to be bad; he doesn't want to be a Nazi. He was only raised that way, right? Well, except that's all a ruse, designed to toy with this "weak" Oliver.

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After a teary-eyed Ollie pours his out his heart to the doppelganger, recalling the devastation of losing Tommy -- "You weren't just my best friend; Tommy, you were my brother" -- Prometheus goes in for the emotional kill. When Oliver pledges to protect Tommy's family from Earth-X's Fuhrer, Prometheus looks relieved for a beat, and then says, "Then you really are a special kind of idiot."

This Tommy Merlyn wears more than one mask, and with that final one removed he continues his assessment of Oliver Queen and his world. "Is everyone here really so weak?" he asks. "The Reich will change that. The weak will be eliminated, and your entire world will be enslaved. And you -- you! -- won't be around to witness it."

But then again, neither will Tommy. His dire warning about the Fuhrer's plans for this world complete, he removes a suicide pill from his mouth and kills himself in front of Oliver, who's unable to save this Tommy Merlyn either.

The Arrowverse's 2017 crossover, "Crisis On Earth-X," concludes Tuesday, Nov. 28, at 8 p.m. ET/PT with The Flash, followed at 9 p.m. by DC's Legends of Tomorrow.