Baba Yaga

 is the answer to the phrase "my enemy's enemy". . . don't count on her as an ally, but if you are up against The Dark One, she might just lend a hand.

In the Comics
After being pulled away from the Dream Eater, the Piper would have been happy to see anyone, well, almost anyone. Upon seeing Baba Yaga standing there, he tried to escape her almost as much as he did the Dream Eater. She taunted him, by using his catch phrase, "It's time to pay the Piper," against him.

Quotes

 * "What are the words I'm looking for here? Oh, I know... It's time to pay the Piper." - The Piper