For storyline purposes, Esifex is only interested in Supporting with other casters. All discussions should start out as rather left-field, confusing the shit out of the other caster, but by the third support, Esifex would be more receptive to things that could be mentioned in other supports (for example, the merits of cooking being discussed with the other characters... Esifex would mention something along the lines that 'having a hobby, like cooking, could be good for a foundation in reality.')
All of Esifex's supports conclude with a more stable-minded conversation with Esifex. If Esifex is present during the final battle, her quote should be something along the lines of, "Everything exists. When they stop existing, though... that's different." Vague and makes no sense out of context. Her mind is screwed up like that.
Death quote will be 'My foundation in reality... it's crumbling...'
Otherwise, pick 'n' choose who my supports are. I'm really not that picky.