Mai is at her best when she's seething or devastated. She is engineered for suffering and loss to a metanarrative degree. Saki, at least, is unaware of her position as a designated loser and will consistently make the effort to disprove such a theory. This in turn fills her with confidence despite her many blunders. Mai however has the intelligence and self awareness to understand the futility that her own will poses to the greater narrative. She will not marry her sister simply because she has no sister. She will marry Rentarou simply because she cannot repress her adoration for him. She knows this. Rather than a sense of tsundereness akin to Karane, It seems Mai's repression of emotion comes from a spirit of rebellion. One last shred of individualism to delude herself into believing she has more control over her own life than she holds. What Mai doesn't know is that the Rentarou family is a well-oiled machine, and she is a cog.
