After all, he is the Master of the Dream Realm, not omnipotent in reality.
Fu Qian doesn't mind helping Vivian to directly crush Goto Hi, but materializing two personalities into two faces was already the limit of what he could do.
That's even when the target is a spiritual entity.
If he exerted slightly more force, the dreamscape would become unstable.
So, in fact, Fu Qian merely provided Vivian with an opportunity for a fight to the death.
Of course, she didn't waste this opportunity. Even with nothing but her shattered and lingering soul, she did as his sister said, "took care of that guy outside."
...
The final boundary was now before his eyes— in theory, crossing it meant leaving behind the Miracle of the Sea of Ashes.
Bearing scars all over, Fu Qian, now with a much more ferocious appearance than when he entered, took one last look behind.
