Ghost's main goal is to save herself from an unspeakable fate, and her determination to do so is such that she will endanger small children and manipulate the Quantum Realm. She can also get emotional, even though she has good reason to. Ghost is also very perceptive, something demonstrated by how she calmly interrogated Ant-Man, Wasp, and Dr. Hank, before speaking in a firm, biting tone and then speaking aggressively when things became more serious. After she was saved, however, she came to see her own life as worthless, thinking she deserved to die for what she had done to prevent just that, though her consolation with her adopted father seems to have mitigated this somewhat.
Ghost was an enemy of Iron Man's who had fought him several times in the past. However, after one of Ultron's failed schemes to destroy the world resulted in Terrigen Mists being released throughout the world, causing people with dormant Inhuman genes to undergo Terrigenesis and become Inhumans. It turned out that Morley was one of those many people, and upon emerging from the Terrigen cocoon, found that he had obtained actual phasing powers, no longer needing to do so with his tech.
Ghost appears in Ant-Man and the Wasp as the main antagonist alongside her adopted father, Bill Foster, though her actress (Hannah John-Kamen) doesn't consider her as evil. Her main objective is to save herself from a fate worse than death that surfaced as a result of a quantum accident that befell her in her childhood, but she is ultimately rescued by Janet van Dyne. This makes her feel horrible because she had been intending to use her.