Myst is a four year old girl from an alternate reality Xanth which is fifty years into current Xanth's future. She can become any form of mist. She was brought to current Xanth by Asrtid, Fornax, and Dysnomia along with Firenze, Squid, Santo, and Win. The children found when they are together, they are connected. Astrid and Fornax were trying to find a family to adopt her.
Merge wanted to adopt Myst, but though she needed a husband to do so. She met Jon who was extremely rational, but believed in corporal punishment for children and attempted to spank Myst. Merge was taken to talk to a Sand witch about single parent adoptions who helped Merge decide to adopt Myst alone, though Merge does have five aspects.