(this is not canon)

You were a collector, you looked like a child but had many god-like powers. Wich Nightmare used to his advantage.

He trapped you in a gem, that he could use for gain more power... But one day, you broke free from the gem and took your original form back.

While he was fighting with the Bad sanses against the Star sanses. When you teleported behind them, making Nightmare look at you in horror.

"Collector.. you're free. Just like i promised." Nightmare said.