ALSO I met Brian Herring (the guy who does the puppetry work for BB8 and the porgs) and he told me that between takes Adam Driver would run around on set to stay in character (?) so everyone on set started calling him “Kylo Run”
The fight with Rey and Kylo, it’s intense. I’d been training really hard, for this exact moment. There’s like eight people we’re fighting and it’s a lot going on. And the minute you just miss one thing it’s very hard to get it back. But Adam is incredible, he literally gives the most insane performance every time.
“In the first trilogy, the hardest thing Luke could be told in that moment was that Vader was his father. That turns everything on its head for Luke. It takes away all the easy answers and makes him face the hardest thing—which is that, ‘I no longer have just a bad guy I can hate. Suddenly that thing that I thought was the bad guy is actually a part of me.’ For Rey, I think it’s the exact opposite; if she were told that she’s related to this person, or Luke is her this, or whatever, that’d be the easiest thing she could hear. That’s everything she wants. That would instantly define what her place is in this universe. So, to me, the equivalent of ‘I am your father’ is‘No, you’ve got to stand on your two feet, there are not going to be those easy answers here for you’” —Rian Johnson in the Balance of the Force featurette for TLJ
Reylo Source 