Sister Mary Georgia is relegated to the kitchen to wash the pots and pans.  Her habit is bare and dirty, her skin rough from the constant abrasion and washing.
Sister Marie is prompt and efficient, her commands are met immediately. She reigns over the ward.

Sister Benedicta is regal and bewitching. The ward belongs to her. At night, when all is quiet, the patients gather before her in a circle of obedience.

Sister Christian is evil and calculating. She wants power and submission. Bow before her.

You say whom your sister is. You dress her as you want for your Halloween images. Add the White Nun to the scene for even more creepiness. It's time to shake up the asylum!