The Cannon Fodder White Moonlight's Survival Guide

As a young lady of a duke's household, her eldest legitimate sister is the empress and heroine of a palace-intrigue romance, her second eldest legitimate sister is the heroine of a domestic-intrigue romance and a prince's consort, yet she is merely a cannon-fodder concubine's daughter. That would be bad enough, but she is also the white moonlight in the heart of a twisted villain, the kind who ends up being killed by him. So Xie Qingyuan decides to cling to her heroine sisters for protection, but somehow, she ends up drawing that man over. Xie Qingyuan thinks a gentle personality plus maxed-out abilities isn't bad. But something seems off. Could she have accidentally driven the gentle male supporting character to turn evil? Theme: