I am becoming more and more interested in the fact that while Finn and Hux call Kylo Ren “Ren” as if it is his surname and they are being formal with him, Rey refers to him as “Kylo” like it is his first name.
Which would mean that Rey is much more intimate with him than people who have worked with him for years.
If they wanted to create that distance, but didn’t feel that calling him Ren would suit Rey’s character, she could have called him Kylo Ren.
If they wanted to show that the conflict is actually between Luke and Kylo Ren, they could have had Rey call him your nephew.
But they don’t. She calls him Kylo. She calls him by his first name, which has been framed as somewhat intimate in regards to how everyone else refers to him.
And that gives me confidence that after Han, she’ll be the first one to call him Ben in years.