The Queen of Winter, known as Beira to her friends, rules the Dhibir Court. The members of her court were once Inisfail Fae, but were banished to Alba.
When Shisti went to the Inisfail Court, the Queen of Winter put a spell on her to weaken the Inisfail Fae from the inside.
More recently, the Queen of Winter used magic to impregnate Shisti with a second baby, alongside the child of Vilkos.