In the final sequence of EPISODE VII, we see Rey’s true awakening. If we view the escape from the Starkiller Base as a more direct portrayal of her escape from the belly of the beast, then this sequence represents her passing through the World Womb and crossing the more significant threshold to become a true mythical hero.
After witnessing Han’s murder at the hands of Kylo Ren, Chewbacca manages to get in a hit from his bowcaster that helps to weaken him (which in no small way contributes to all of their survival). Chewie is pinned down by stormtrooper fire and detonates the charges they’ve planted throughout the compound. This prompts Rey and Finn to flee without first re-grouping with him.
Outside, they face Kylo Ren, who has also managed to escape the destruction of the compound. Kylo is visibly dissatisfied with the result of his confrontation with Han Solo, which he had hoped would eliminate the emotional conflict within him and clarify his purpose. Kylo allows his rage to control him. Instead of resolving his inner conflict, the experience appears to have left him even more lost and confused than he was before. Kylo is still interested in Rey, but when she attacks he slams her into a tree with enough power to leave her unconscious (and, from Finn’s perspective, possibly dead).
Finn’s journey runs parallel to Rey’s in this film much like Han’s journey ran parallel to Luke’s in EPISODE IV. Facing Kylo Ren is Finn’s opportunity to stand before the threshold guardian and have his own merit tested. Just as Han ran interference on Darth Vader to give Luke enough time to take his one in a million shot against the Death Star, Finn keeps Kylo Ren busy long enough for Rey to get back in the fight.
Finn acquits himself well enough, considering he has no Jedi training or demonstrated Force-wielding ability, but to some degree Kylo is toying with him. He could just as easily toss Finn into a tree, but he is confident that Finn is not a threat in the way that Rey would have been. This choice betrays Ren's feelings toward the two of them. While he clearly is unconcerned with Finn as a threat, he preemptively shut Rey down before she could confront him. His fear of her has allowed much of his anger to be directed at her as well, but this may not be the only reason. We don't actually know anything about Rey and Ren's relationship at this point. There may very well be even clearer reasons for his fear and anger toward her that have not yet been revealed in the story.
Kylo’s anger is only directed at Finn at all when Finn manages to get in a couple cuts during the duel. As soon as this happens, Kylo dispatches Finn with relative ease. The only reason he doesn’t kill Finn in the fight is the fact that Rey wakes up and intercedes.
Despite the fact that Ren wins without a whole lot of effort, some fans have complained that a janitor should not have any ability to fight a Sith Lord in a lightsaber duel.
"Say that to my face, fanboys."
To this, I have three points of rebuttal:
1 – Finn is not a janitor. He is a well-trained First Order Stormtrooper. Part of that training involved working in various locations of the base and performing various functions, even menial ones. There is no Special Sanitation Unit of the First Order Stormtrooper Corps. As I have stated before, Finn was trained to use melee weapons and, while that training did not include lightsabers, holding a lightsaber doesn’t require special Jedi magic. Anyone can potentially do it, but just as it is with piloting a spaceship, Jedi have preternatural intuitions and reflexes that give them the potential to do it better.
2 – Kylo Ren is not a Sith Lord. He is trained and has a lot of natural Force ability, but we don’t even know if Snoke is a Sith Lord. I strongly suspect he’s not, but if he were Kylo would at best be his apprentice. According to the prequels, the Sith philosophy only allows for the existence of a single master and a single apprentice at a time. I don’t know why I think this, but I think Snoke is somehow something older than the orders of the Jedi and the Sith. It would be interesting if the name of the First Order refers to the fact that it predates them as well.
3 – Finn doesn’t do so great in the fight. Kylo is badly wounded and underestimates Finn, which allows him to get some good shots in, but the second Finn reveals himself to be even a minimal threat, Kylo makes short work of him.
Kylo’s control of the Force is uncertain where Rey is concerned. Throughout the film he has managed to score successes with impulsive attacks like when he made her go to sleep on Takodana and when he shoved her into the tree, but his footing is much less sure when they are involved in more prolonged engagements. When he tried to read her mind in the interrogation room, she was shockingly able to read his as well. When he calls out to the lightsaber that once belonged to Luke and Anakin Skywalker, it is drawn instead to Rey. The ensuing duel proves him to be just as uncertain in his abilities. Despite Rey’s total lack of training (with lightsabers and the Force), she holds her own against him.
There are several other factors at work that influence Kylo’s capability during the fight. He is physically weakened by the injuries he sustained at the hands of Finn and Chewbacca. He is also shaken by his murder of his own father, which did not purge him of all tendencies towards goodness or guilt as he’d hoped. He is also quite obviously torn by his feelings for Rey. Just as when he appealed to Han for his help on the catwalk, he is being sincere when he appeals to Rey to join him.
"I've got a spot open in my band. Do you like Industrial music? We mostly do NIN covers, but I'm working on some original stuff. We haven't actually played any gigs yet. Just think about it and let me know. No pressure."
This scene may cosmetically mirror the duel on Bespin when Vader made the same appeal to Luke (possibly reinforced by the fact that the Bespin duel was a part of Rey’s Force vision), but one important difference is that this is not in any way related to the father quest/atonement that is integral to every major Jedi duel we have seen in the other films. We have seen Jedi battles where this dynamic was not in play, such as Qui-Gon's duel with Darth Maul in EPISODE I and Anakin’s final duel with Dooku in EPIDOE III, but in both cases the fight had no emotional element and no critical connection to the larger story. The fight with Maul was the opening act of the new trilogy, existing entirely so that there would be a lightsaber fight in a movie that otherwise did not require one. Anakin’s defeat of Dooku happened in the first act of EPISODE III, unceremoniously disposing of what appeared to be an important villain just so we could see the strengthening of Palpatine’s influence over Anakin.
"This is only slightly better than what Jackson did to me in RETURN OF THE KING."
One could argue that the Kylo/Rey duel at the end of this movie is just as superfluous as the duel at the end of EPISODE I and is shoehorned into the movie for the same reason. I don’t think that argument holds, because this fight isn’t just the product of superior plot construction, it also has a defined and relatable emotional tie-in to the story we have been watching. Maul comes out of nowhere in EPISODE I, has no real connection with the plot at large or the characters, and his hatred of the Jedi (whom he has never met) is only established in an expositional line delivered in a throwaway scene that doesn't actually explain anything. He never even has any dialogue with the Jedi. There is no connection between them. He is simply an obstacle that must be overcome, but even in that regard he’s irrelevant because once Obi-Wan defeats him, Obi-Wan has no further contribution to the resolution of the film.
Even the eternal rivalry between the Jedi and the Sith is a poor motivation for either side, since it’s stated in the movie that there hasn’t been a Sith Lord for over a thousand years. You can’t argue that there have been ronin Sith running around for that entire time because the movie also states that they always come in pairs. Even if Yoda is wrong about this, the fact that he believes it indicates that he hasn’t ever seen a Sith without a master. He is the oldest and wisest of the Jedi and he's almost 900 years old. If the Sith haven't been around for a thousand years, that means no living Jedi has ever seen one. So even the abstract struggle between the Jedi and the Sith is archaic and certainly shouldn’t be cause for personal enmity on either side. It’s a little unsettling that they are all bent on each other’s destruction over events that are, to them, merely a matter of history.
That is not the case at all in the climax of EPISODE VII. Kylo and Rey have are at odds not because of outward circumstances, but because the events of the story have actively put them against one another. Kylo is, by the end of the film, more interested in Rey than he was in what he was doing when the film began.
Rey’s interest in Kylo is solely based on her personal experiences with him. She has no interest in becoming a Jedi or for that matter joining the Resistance. Like Luke in the original trilogy, all of Rey’s actions are based on moral choices she makes regarding each individual situation. She rescued BB-8 from the Teedo because she didn’t think it was right for the Teedo to capture him. She agreed to get BB-8 to the Resistance because she felt it was the right thing to do. Even as she faces Kylo in a duel, she is fueled by her anger over the murder of Han Solo, but she stepped in to protect Finn. This, I believe, is the reason the lightsaber came so readily to her hand.
"Eat my moral superiority, Emo!"
Kylo also represents a mythological threshold guardian for Rey on a physical and spiritual level. He physically bars her from escaping Starkiller Base with Finn. Spiritually, it is only through this confrontation that Rey accepts her true connection to the Force. She swore never to touch the lightsaber again, but when it was necessary to defend her friend, she willed the saber to her hand so effortlessly that she didn’t realize she’d done it. This action signifies her total acceptance of that destiny and the responsibilities it implies. This is further confirmed near the end of the duel, when Rey finally closes her eyes and trusts the Force. This gives her the strength to defeat Kylo, but it looks like she's still being driven in part by her anger, so she still has some growing to do.
Alan Dean Foster's novelization of the film sheds some light on this moment. Rey actually hears a voice (presumably that of Snoke) urging her to kill Kylo, but she resists. If this was Snoke tempting her to kill Kylo and take his place, then we can at least infer from this that she is not so guided by her anger that she is compelled to obey.
The ferocity of their battle is evidenced in the damage it wreaks on the planet around them. This is probably attributable to the fact that the Resistance fighters are literally blowing the planet apart, but the destruction corresponds with the intensity of the duel. In a visual homage to the legendary duel between Obi-Wan Kenobi and Anakin Skywalker, the ground splits open between Rey and Kylo, separating them with a chasm that leads down into a river of molten magma. This gives them both the opportunity to break away from each and escape before the planet explodes.
The chasm also visually depicts how Ren and Rey represent separate halves of the Yin Yang
Having recovered the Millennium Falcon, Chewie picks up Rey and Finn. In an equivalent stroke of serendipity, Hux is commanded to swoop in and recover Kylo Ren as well. They all fly away and the planet explodes, because at this point in the film something needs to explode, I guess.
Thus ends the first duel between Rey and Kylo Ren. It's safe to assume it won't be their last, but with so many unanswered questions remaining about their relationship and the future of the Force in general, it's impossible to predict what will happen next. Always in motion is the future.