She spent the last month learning about the soul pact and how to utilize it. The soul pact was an agreement between two souls to share one body, it is funny cause it is called the soul pact and then sounds like the two souls have to be in agreement but that is all a lie, someone could enter a soul pact with you without even you consent, just like that woman had done for that dragon and how she was about doing for the Alteazor.
Another scary thing about the soul pact was its repercussion. Once a soul pact has been started by one soul, it can not— no can never be broken by anybody, not even any of the two souls. If anyone from the outside tried to break it, they would receive the fate of those two core demons and if any of the two souls in the pact tries to break it, what was happening to the Alteazor would be it's fate.