Hello. I'm working on a story right now and I have a character who has multiple personality disorder and has hallucinations. Is it possible for her to have conflicting dualities, like feeling and reason?
Of course it's possible.
I'm not an expert but, as I understand it, people who develop alternate personalities do so to dissociate from situations that are unbearable (e.g. abuse or trauma during childhood). Each personality is the repository for feelings and attitudes that in most people would resolve themselves into a whole.
Curiously, Dramatica views a complete story as a model of a mind attempting to resolve a problem or achieve a goal. In this model, the characters represent different motivations within the mind, some that conflict with each other, some that complement each other, and some that require each other. It sounds a lot like MPD, doesn't it?
This is probably why there are many stories in which scenes take place within one character's mind and different characters represent different aspects of that one character.
For instance, a character might have a dream in which a group of characters argue over an issue. Or a character might imagine an angel and devil (representing conscience and temptation) looking down on him and arguing over what he should do. These characters are facets of the main character's mind, which usually resolve when the character makes a choice.
It would be equally valid to have two facets that represent reason and emotion.
Of course, you would do well to do some research on MPD to be able to depict your character with authenticity.