For a little while we can live vicariously as a hard boiled private eye or a brave soldier or a wise-cracking rogue with a heart of gold. That's one of it's chief attraction, and that's where the escape in escapism takes us.
In the pursuit of these fantasies, our own righteousness is guaranteed by the author, of course, who's always on our side, and we are freed to exercise our angry and violent impulses without concerning ourselves with their consequences. Heroic righteousness allows us to kill, main and brutalise our enemies without restraint. There's nothing we can't excuse ourselves if we know our cause is right.
Science fiction and fantasy give us a further out: in these genres our enemies can be literally non-human (rather than the literary inhumanity that more Earth-centred foes in other forms of adventure fiction, the Soviet spies, yellow peril and Middle Eastern extremists). Perhaps most famously, the Orcs in The Lord of the Rings set out a kind of enemy one can kill guiltlessly, as they have no admirable qualities whatsoever, and this has certainly set a pattern in heroic fantasy that's been formalised in the D&D generation of writer with their weird numerical categorisation of racial characteristics and the literal moral compass of alignment.
Norman Spinrad spotted the worrying aspects of all this in the 70s and highlighted it with brilliantly cold clarity in his wonderful novel, The Iron Dream. Spinrad saw beneath the harmless fantasies at the murky longing for power and violence that lay beneath.
