See how often they participate in the script: HERE.
Character Story: Having lived his entire life in the Twilight Realm, Zant grew tired of feeling like a prisoner. He proclaims himself King of Twili with help and power from Ganondorf and invades the Light World, planning on completely enveloping it in shadow.
Race Story: Descendants of sorcerers of the past who were banished into a Twilight Realm whose only entrance is a mystical mirror located in the Western desert. They are the first to suffer from the hostility of the darkness.