Dang if you guys can't handle the slow burn then just leave, this isn't gonna be a novel where Ruby gets over her abuse super fast, she's enduring 2 lifetimes worth of abuse and it would be unrealistic as hell for her to open up to any stranger, let alone the guy who was supposed to kill the character she's possessing. If you want something faster then go find one of those manga where the abused is a child who doesn't know better and opens up to their savior instantly.
Dang if you guys can't handle the slow burn then just leave, this isn't gonna be a novel where Ruby gets over her abuse super fast, she's enduring 2 lifetimes worth of abuse and it would be unrealistic as hell for her to open up to any stranger, let alone the guy who was supposed to kill the character she's possessing. If you want something faster then go find one of those manga where the abused is a child who doesn't know better and opens up to their savior instantly.