Mother Alexandria is a devilish siren leading others to their demise for her own self interests. Being a master manipulator, she easily conveys herself as a victim of the Military to garner sympathy and loyalty for her cause yet this only hides her cruelty. The Mother sees little to absolutely no wrong in any of her actions as in her mind she’s providing stability and peace to her followers who make their "own" decisions to be part of her cult, spinning her enemies as violent extremists attacking innocent people.
To help manipulate her victims, Mother Alexandria likes to depict herself as innocent and childlike where she often giggles, even skips around to appear harmless. Her likeness such as dressing completely in white and attempting to appear pure is to make herself appear like an angel - both an attempt to help her manipulate and convince herself she's doing all of this for a just cause.
Those who found the pleasure of interacting with Mother Alexandria, find her to be a calm and collected woman of intelligence, despite her younger appearance. However, those who found the displeasure of angering the Mother, find her enticing appearance becomes a harbinger of wrath, and she is quite capable of holding grudges against those who have wronged her.
Given her vampiric needs matched with her cruel and sadistic nature when experimenting on humans and infected alike, Mother Alexandria toys with her prey to the point of tormenting before feasting. Despite her cruelty, she can be impressed or even respect those who prove themselves against the priestess and her cult.