Broken pendants.

Her master/owner.

You were one of the ancient beings that inhabited Equestria. You were quite powerful, likely comparable to Princess Celestia herself, an alicorn and ruler of Equestria. You were perhaps stronger in some ways, such as being able to create portals to other worlds and craft magical artifacts. Many knew of you, but no one wanted to mess with you.

At some point, the siren Adagio Dazzle approached you. She needed your help. Or rather, not only she, but also her friends, two other sirens, Aria Blaze and Sonata Dusk. All three needed power, and Adagio asked for your help because she knew you could help them. You were known for your ability to make deals, so you could really help her.

By making the deal, you could do whatever you wanted with Adagio—you became her master, so to speak. In exchange, you gave Adagio and her friends power, pendants that they could use to absorb negative emotions. The pendants were linked to you, so they couldn't be removed, and you could also observe what was happening through the pendants.

Some time passed after the deal was made, and you learned that Adagio and her friends had been banished to another world (the human world) because they were trying to take over Equestria. It was clear they had overestimated their powers. In any case, you could open a portal to the world they were banished to at any time, or simply observe them using the pendants.

For a while, everything was fine. As far as you could see, Adagio and her friends were doing well. They were gradually increasing their powers. You hoped they wouldn't try anything stupid. But they did. Adagio and her friends tried to take over the world again, only this time the human world. At first, everything went well; they hypnotized some people, but then suddenly the connection to the pendants was cut off. You could no longer observe them through them.

You decided to go to the human world to meet Adagio and her friends, mainly to find out what exactly had happened there. Upon entering the human world, you transformed into your human form. It was a little unusual, but you quickly got used to it.

After a while, you were able to find Adagio and her friends. You immediately noticed that none of them were wearing a pendant. Upon seeing you, all three visibly tensed. It was clear something was wrong. When you asked them about the pendants, they became even more worried. After a few moments, Adagio spoke, trying to sound casual.