This is picking up right from the point of Tangled where Mother Gothel falls down the tower and "dies"

She let out a frustrated sigh and pushed her grey curls behind her ears. She was soaked. Water covered her from head to toe as she dragged her old body out of the river she had landed in.

That stupid girl, she thought as she rung out her hair. The woman glanced down at the water. It was dark out, but the moon shone brightly, making her reflection in the water crystal clear. The bags under her eyes were sagging and her chin had doubled. Spots had grown over her face and wrinkles had formed just about everywhere. She growled and began to smash her hands in the water, making her even more wet than she already was.

"I must say, Gothel, you do not look well." A slick, slimy voice said from behind her. Mother Gothel didn't jump. She knew who it was. He did save her life after all.

"Shut up." Gothel snapped over her shoulder. "You are useless to me."

The man stepped out of the shadows. He was tall, gaunt and pale. His hair was dark like his blackened heart. "Remember it was I that helped you retrieve the girl in the first place. Without my help, you would have died years ago."

Gothel clamped her lips shut, remembering the deal she had made with him. He had promised her the golden flower, had helped her break into the castle to steal the girl, and then built the tower for them to live in. He was right. Without him Gothel wouldn't have gotten that far.

"I'll kill him." Gothel sneered. "I'll kill that Flynn Rider!"

"Patience, Gothel." The scary man replied. He placed his hand on Gothel's bony shoulder. "We have much more pressing matters to worry about."

"You mean you have more pressing matters, Pitch." Gothel snapped, shrugging off his hand. She looked up into his serious face, glaring into those pit like eyes. "I don't work for you anymore."

"Oh, but I think you might." Pitch Black replied. He kneeled down next to Gothel, placing his hand on her shoulder blade once more. "For only I can give you what you seek."

Gothel chuckled. "You already did that and now look where it brought me. I am that ugly old woman I was from the beginning."

"You have been that ugly old woman all along." Pitch said. Gothel glared at him. "There is darkness in your heart, love. I like that darkness for I have it as well."

"What is my prize?" Gothel asked after a hesitant pause.

"You will have the girl back." Pitch replied. "And you will also get the revenge you seek."

Gothel smirked wickedly, "And what are you asking me to do?"

"To wait." Pitch said as he rose from the ground.

"What exactly are we waiting on?" Gothel asked, rising with him. Pitch was walking away with his back to her. He looked over his shoulder at Gothel, smiling that sly, wicked smile of his.

"For the Guardians."

"You mean the Easter Bunny? Santa Clause?" Gothel chuckled.

"A day is coming when even those great guardians cannot withstand the darkness. It will be so great that they will need to call upon fresh blood." Pitch paused and looked up at the moon. "And he will be the one to choose them."