The series had to potential to trip one of do-not-finish wires: The wise yet hot guy guides the completely ignorant girl, and ends up taking her to bed – shades of teacher abuse.
Last book, someone anonymously sent brand-new, ignorant Prime Nevada some books to study. Yes, of course it was experienced Prime Rogan, but she did the studying on her own and had very little debt to him over this. This book, she uses both her book-learning and some inborn skill to terrorize a family of fighters.
Rogan is entirely ethical, and underhanded, about chasing off The Other Suitor ™. Yes, both. Beautifully done.