Above all else, Icebella values her isolation from the world. It is death to enter her realm -- not only because of the freezing climates but because she will actively seek out and kill any who enter her territory without an express invitation, which she never extends.
Legends say that she once had a warmer heart, but it was pierced with a shard from a broken magic mirror and caused her heart to become frigid. Legends also say that a single kiss from her can chill a man's soul, and a second kiss will cause him to freeze to death. Her only pleasure is in the great Crystal Cave in her realm.
Around the time that Mordack kidnapped the Royal Family of Daventry, a yeti invaded her crystal cave. It could not be driven out, and this infuriated the frigid queen. Shortly thereafter, Cedric the Owl and King Graham of Daventry entered her realm without invitation. The queen sent her wolves to capture the owl and lure Graham to her. Whilst in captivity, Cedric explained their quest, though Icebella was unmoved.
When Graham reached the palace, he was escorted in by her wolves to her throne room. There she ordered the wolves to set upon him. Quick thinking, Graham played music from the magic harp he had received from Princess Alicia. The music, fueled by the power of love, managed to melt Icebella's heart just a tiny amount -- enough that she agreed to allow Graham and Cedric to continue their journey if the human king could defeat the yeti.
He returned successfully, having slain the yeti. Icebella kept her word and allowed the king to pass. This marks King Graham and Cedric the Owl as the only uninvited guests known to have survived entering Icebella's realm.
Queen Icebella is a character in King's Quest V: Absence Makes the Heart Go Yonder.