The origins of Maria are rather bitter due to her looking like Todd's late best friend who he once had feelings for.
Maria is not like Todd despite having a human body. She was created to spite Todd, to weaken him, to destroy him from the inside, to lower his guard, and to manipulate him just for the right moment to dispose of him.
After being adversaries to each other, they have been seen working together but rarely. It is undetermined if she'll eventually try to kill him, or if she will remain a helping hand. It is also unknown what she is thinking.