Many characters in fiction are beaten when younger but, not daunted by their setbacks, they set out on a tough training programme in order to become stronger than their nemesis, ready to return and kick some ass.
This can be a character arc either for a PC hero, or for an NPC enemy. To set one up, you just need an inconclusive encounter that leads people to become rivals. Introduce Mr Miyagi, or Yoda, stir, and hey presto!
Commentary by memnarch (who has not seen the movie)
Uhhhhhhhhhhhhhhhhhhhh....... what? .....What?? No, like, seriously. What???
What happened to Kylo the temper tantruming terrible tyrant? Where's all of this coming from? I know I joked before about Kylo Ren being a Darth Vader wannabe, but this is like the exact opposite of what a Sith should be doing. Dropping the helmet that actually makes him look cooler, carefully holding out a weapon to show it off without threatening or menacing anyone; what's Scar-head Snoke gonna think? And this is all actually happening in the movie too!
There's gotta be something big going on in the actual conversation here that I'm missing out on.
Transcript
Kylo Ren: Meanwhile, Anakin became a powerful Jedi.
Kylo Ren: I slowly realised that his midi-chlorians granted me Force powers too.
Kylo Ren: When Luke Amidala set up his new Jedi Academy, I joined, eager to fulfil my potential.
Kylo Ren: I learnt that Luke had killed Anakin, depriving me of one vengeance.
[SFX]: thunk {Kylo drops his helmet onto the catwalk}
Kylo Ren: I vowed to become more powerful than Luke and kill him. But I tried too soon and had to flee.
Kylo Ren: My primary target would be easier to kill with this sword. But you were much harder to track down.
Kylo Ren: “Han Solo”, the identity thief, had vanished.
(No Name): Chewie, I told you there was a good reason to become Ignazio.
Chewbacca: Twenty years before you knew there was a good reason. That’s some forward thinking.