I, the Demon Lord, Let Us Both Sacrifice One Life

What should I do if another protagonist brings a system, but I bring a demon king who wants to take away my body every day? Waiting online, it's very urgent! My family was massacred, and I became the only survivor. I also became a new prison for the demon king Xuan Ge in my body. He covets my dragon blood and body, and I want to borrow his power. Facing powerful enemies from all directions, I silently retreated behind him: "Boss, the enemy is too strong, I can't stand it anymore." Xuan Ge controlled my body and suppressed the whole audience with one blow, showing the true nature of the demon king. From then on, I was responsible for causing trouble and he was responsible for making peace.