Is this a made-up story? Maybe. Maybe some part is made up, but it feels about right to me.
Pavel, Ruslin and Dmitri aren't the kind of monsters we might expect of fascists. They might not even be fascists yet. Hannah Arendt, writing about Adolf Eichman, coined the phrase "the banality of evil", and these three certainly fit, but all is not fascist that's banal.
Our three captors seem to be carrying around enough hate and anger to be willing to kill, and with time they'll learn to focus it on the hate object of the day, starting with Russians. (Other Russians, not themselves of course!) They seem to have nothing they believe in or care about enough to die for, except to prove something about themselves. Backed by enough weaponry to feel invincible they'll act tough and brave, but when faced on equal terms with battle-hardened soldiers who care enough about their cause - and each other - to die for them, they'll turn and run.
Sometimes terrified, humiliated and shamed by much less heavily armed partisans, they'll feel powerful and invincible taking their revenge on unarmed "enemy civilians". Endlessly abused and denegrated by their commanders and foreign "advisors", they'll strut with pride in their skill at killing and the thrill of seeing the fear of their victims. Thus they will, if they live long enough, grow into their fascist roles and become the murderous but ultimately cowardly bullies you'd expect.
Veterans of the wars in Iraq, Afghanistan, Vietnam and Korea may recognize their type: "allied troops" who were great at torturing and killing prisoners and unarmed civilians, but turned and ran in disorder all the way to Pusan in 1950, panicked at Pleiku and ran all the way back to Saigon in '75, and dropped their guns and their pants and ran for their lives before ISIS last month at Mosul.