Millia was a friend of Glinda, after they met at Shiz.
She was one of Glinda's cronies back when she was Galinda. She later married Boq and moved with him to Munchkinland where they had several children. Though Boq writes that she was miserable there, and often attempted suicide. The suicide attempts happened because she was put in a lower social standing because she married Boq. She is still alive twenty years after leaving Shiz, and has "kept her figure," in Elphaba's mind.