|The pure Robin|
She has a second personality which comes out when she bleeds, which is a blood-thirty persona that calls upon God to battle her foes. While in this second personality, she acts somewhat more like Houbara and Crow.
Robin claims to be pure as opposed to her "dirty and feral" sisters and has devoted her life to exploring the teachings of her gospel (some form of Christanity, although there seems to be an entirely new book added to the Bible) and preaching it. She is at harmony with nature, unlike Crow and Houbara who live in it but seem to be at odds with it. She thinks she has a good singing voice, but Crow seems to disagree. She is very judgmental of those who don't share her beliefs.
She has a second persona that only comes out when she has been hurt and is bleeding. In this persona, she becomes murder hungry and calls upon God to wreck vengeance on her foes, commanding him with her staff. It is implied that God is actually scared of her in this persona, which is why she's able to order him around. Crow and Houbara vastly enjoy this side of Robin more than her normal persona.
Robin has a staff which she can do various attacks with, but she is rarely seen using it despite having a expertise in it. In her second persona, she is far more powerful using it, and is able to command God to attack with thunder and other disasters. Unlike Crow and Houbara, she is able to count well beyond their comprehensions and read incredibly well. Although she can write, it is implied that her writing is not very good.
Robin is also mostly immune to any disease for unknown reasons, able to eat raw, dead animals without signs of sickness or fatigue later.
Robin is the most civilized out of the four, and thus they are at odds with each other. Due to Robin's cleric career, she often tries to "tame" her sister and get her to believe in god, but this often ends with her place being trashed. Despite this, Robin loves her sister and just wishes the best for her. Crow prefers Robin's alternate personality, which is a battle-obsessed persona with a lust of showing her foes judgement.