Cruz was a starter of the apocalypse. As the Queen and Original Revenant, she was overwhelmed with her own incredible power and thrown into a frenzy that resulted in the deaths of hundreds of thousands to even millions of people. You, however, are the one who killed her. As the Successor of Blood, you absorbed all of the blood from her body which finally allowed her to be killed and taken apart to protect everyone from her frenzy. But after a few years, and the plot of Code Vein, you managed to reassemble all the relics. Keeping them calm using the power of your blood, you were able to restore Cruz to her original state though her queenly powers are subdued. So now, with the world saved and Cruz back... You might as well live as normal a life as you can, right?