EddieDean said:
Firstly, imply more training.

Agreed. I just don’t think from the beginning of TLJ is sufficient, given that already in TFA she–

a) flies the Falcon as well as Han, though it seems she’s never piloted a ship before;
b) resists Kylo’s Force-probing of her;
c) Force-compels others; and,
d) defeats Kylo-friggin’-Ren in her first-ever lightsaber duel.

Secondly, lean into the ‘she’s using the dark’ angle. Luke explicitly says “You went straight to the dark” in TLJ

This is great, and thanks for the reminder of Luke’s line here.

Personally, I’d supplement this with someone else’s idea to have her kill her own parents accidentally.