"Uhu~ I love you, Mär. We'll be together forever and ever from now on, right? Ahahaha~!' -Elize (Yoiyami no Uta)
Elize is one of the main character's of the 7th Story CD, a mysterious doll who serves as Mär's guide and assistant as he helps the seven maidens get revenge on people who have wronged them. She is a malicious soul whose only drive seems to get revenge on someone or something.
In actuality Elize is the doll that was given to Mär by Elisabeth when they were children and was thrown down the well along with him during the later events described in Hikari to Yami no Douwa. It is debatable how Elize was able to gain life, although it is possible that she is the incarnation of either Ido's will or Therese's thirst for revenge (the latter being implied through the imagery shown in the concert version of Yoiyami no Uta. While she isn't as active as Mär in helping the seven maidens get revenge, at the end of every track she gives a short commentary on the story that has been shown -usually cruel or underhanded in nature.
In the final "act" of Haritsuke no Seijo she tries to convince Mär to forget about Elisabeth so they can continue getting revenge, a suggestion that falls on deaf ears. In desperation Elize tries to remind him of all the fun they've had helping others taking revenge. Declaring that they had made a promise to stay together forever, and that she loves Mär more than anyone else. At Mär's silent declining of this offer, force that was keeping Elize "alive" was banished, leaving only a regular doll in its place.