It was just as easy for that person to assume the identity of the person they had killed, allowing them to take over everything their target held.
One moment of carelessness and everything Cheryl had worked toward for so long would end up being swallowed by another, and her struggles to survive outside of the grasp of her family would end just like that.
If there were reasons why such a thing would not happen when Ash was that person with that type of power, then it would have a lot to do with her needing allies and backing rather than what they possessed.
Moral reasons were holding her back from targeting Ross just as she would hold back from targeting others.
Cerberus was a crime syndicate, and it had many underworld dealings.
It certainly had many bad parts about it, but that was something Ash needed just as much to survive and to attain things that she could not get from anywhere else.
