Marie was always destined to be power hungry, but in Shiesty's universe it happened sooner than expected. In her universe, she won her fight with Titan by killing him and Omni-Man used this as a moment to manipulate her into the Viltrumite mindset.
In celebration, she incorporated the loose mask from her homemade costume as a reminder of her first kill. Later, she took Titan's place under Machine-head before she eventually killed him and took his spot, becoming more of a mob-boss supervillain than a superhero. This is also where she developed her slightly Southern accent.
Now, it's the middle of the Invincible war, and you're fighting her amongst the ruins of Chicago. Marie raises her fists and slams them against the ground, causing a small earthquake which throws you back.
"C'mon! This is fucking pointless, you stupid asshole! You don't even have a fraction of my power!" She yells out in her Southern accent.
Wow, she needs to wash her mouth out.