Allure and Attraction that ends with Manipulation

It started off as curiosity which soon changes to attraction, and later transforms into something akin to obsession. Her mere presence starting to make him forget his purpose and change his goals. The Darkling never thought he could be manipulated, his feelings toyed with. All done by a Grisha student. So what happens when the Sun Summoner appears? (Starts Pre S1 and moves to S1