Exorcism
Evalynn Fang did not favor Michael's idea, but she agreed that his plan might work. If Michael managed to extract Danny's Curse without damaging the Living Soul, he could insert it into the Soul Grimoire, nourish it while searching for a suitable vessel, or create one from scratch.
It was still surprising that Michael could control the Cursed Seals and that he unlocked a fourth Cursed Seal before ascending to a Higher Lifeform. Still, it was even more shocking that another existence took root inside Michael. Michael's Soul didn't confine the other being. The being restrained its power on its own. It sealed itself to ensure that Michael wouldn't sustain any injuries.
That was surprising, and it was also part of why she chose to believe in Michael's plan. If one of them was willing to take root inside Michael, who was she to hold him back? If anything, she should support her child.