It’s been pointed out for a while that Kylo Ren in The Force Awakens has a fixation on Finn that turns increasingly to rage. These moments include:
*Noticing Finn at Tuanul village and intimidating him by unfreezing the blaster beam from Poe’s rifle
*Realizing immediately that Finn was the Stormtrooper who had escaped with Poe
*Flying into a rage at the mention of Finn escaping Jakku with BB-8
*Purposefully inflicting pain and maximum injury on Finn during the lightsaber battle in the woods
What I haven’t seen mentioned is that right after Ren killed his father Han Solo, he recognized Finn and was enraged enough to go after him despite being badly wounded. I didn’t put this in my recent edit because the context would not be clear enough, and I think a text explanation is necessary to show what was going on.
To preface, I always thought it was odd that the camera focused so much more on Finn’s face than Rey’s shortly after Han’s murder by Kylo Ren. She was the one who had built up a rapport with Han, to the extent Ren realized from his mind probe that she saw him as a father figure, and she was the one who wept at Han’s death. Finn and Han had built an understanding and mutual respect, but I never got the sense there was a deep emotional connection between them.
Looking through the movie recently for footage to edit, though, I was chilled to realize that the longer focus on Finn wasn’t the camera emphasizing his reaction over Rey’s; rather, we were getting a Kylo Ren’s-eye view of Ren staring at Finn. The man had just killed his father and he was taking that moment to fixate on his former minion. Here’s what I think was going on:
To recap, after running his dad through and dropping him into a pit Kylo Ren is shot by an enraged and grieving Chewbacca and sadly does not die. He does fall to his knees, though, and looks up:
And what does he see through the smoke and fire from the explosions Chewie set off? Finn and Rey, standing on a ledge high above him.
Then we shift to the shot that bothered me, Finn and Rey both looking horrified and distressed before we get a closeup of Finn’s face.
Except this isn’t just the camera, it’s Kylo Ren’s gaze. Not only is this a close-up of what Ren was looking up at in the previous frame, the angle is also from where he’s looking. As the camera pans in you can see the underside and edge of the ledge that Finn and Rey are standing on. This is because the shot is from the perspective of someone who’s looking up at them from below, i.e. Kylo Ren.
Then the camera shifts directly to a close-up of Ren’s face contorting in rage.
Through this whole sequence of shots the camera stayed very tightly on what Ren was feeling and seeing. We’re seeing Finn through Kylo Ren’s eyes, and watching him stare fixedly at Finn during one of the defining moments of his life. True to form, this works him up to so much hatred and anger that he actually gets up to pursue Finn and Rey instead of curling up in agonizing pain or getting the heck off the disintegrating planet.
Who knows what Ren’s motivation is at this point? Maybe he realized the former trooper had come to help Rey get out and was apoplectic that Finn was foiling his plans yet again. Maybe on some level he blamed Finn for Han’s presence there and therefore Han’s death, as some particularly awful fans do.
More fundamentally, though, I think he hates Finn for making the opposite choice he did. As others have pointed out, Finn and Ren were raised in opposing environments and each denounced his upbringing to go over to the other side. There is evidence that Ren was manipulated from a young age as Anakin was, as Finn was heavily conditioned and brainwashed, but Finn overcame his conditioning while Ren did not.
Finn is, in so many ways, a constant reminder that Ren could have chosen otherwise, that his life could have been different. He could have been at his father’s side. He could have had his mother look at him with pride and admiration. He could have built a connection based on love and trust with Rey. The reason he has none of those things is because he made the wrong choices, choices he remains responsible for no matter what. Finn is a reminder that the choice was always there. Finn takes away Ren’s excuses.
That’s why Kylo Ren fixated on Finn at the moment he killed his father, because his conscience was howling at him and he saw Finn as its manifestation. (Obviously Finn is not any part of Ren, but evil and entitled people often see others as extensions of themselves with no independent existence or worth.) I think Ren wanted to destroy Finn, not just kill him but torture and humiliate him, for daring to listen to the voice Ren had desperately ignored for years.