I think I’ve cracked the potential misinterpretation of incest happening with their kiss with the following dialog:

"Because he influenced the Force to create two dark bloodlines. My grandfather’s, and then perfected with you. You’re his heir, Rey. You… are a Palpatine.”

“The Emperor told me to kill you so that the strongest of us takes the throne. But he’s unaware that we’re a dyad in the Force, Rey… a bond not of shared blood, but power. We can end him and the Sith, and bring a new order to the galaxy, together…”

EDIT: Oh, and this from the beginning - "I pushed you in the desert because I needed to see it… I needed you to see it… who you are. I share the darkness that lives in you, Rey…”