This is kind of short, but I'll update soon.
"Mom!" Phoebe exclaimed. "What are you doing here?"
"I'm here to help you vanquish the demon" Patty said.
"And they were willing to let you come down here?" Phoebe asked.
"No, but I gave them a choice. They could either let me help you willingly, or I would reveal a little secret of theirs" Patty said.
She walked over the bassinet.
"Can I hold them?" Patty asked.
Just then Piper and Leo walked into the room.
"Mom?" Piper said with tears in her eyes.
"Piper" Patty said walking over to hug her.
"Mom's here to help us vanquish the demon" Phoebe said.
"I can't believe you're here" Piper said.
Prue had been standing there silent.
"I think I better put the girls in their cribs" Prue said picking up the girls.
As she walked out of the attic she whispered to Leo.
"Leo follow me"
They walked to the nursery.
"That isn't mom" Prue said. "I can feel it"
"Are you positive?" Leo asked.
"Yes, Mom wouldn't threaten the Elders and the person in the attic seemed a little eager to hold the girls"
"But they're her grandchildren" Leo said. "If you'd never met your grandchildren, wouldn't you be a little eager to hold them? Maybe you're just a little jumpy because of all the demons attacking the girls"
"I just have a really bad feeling about her, and until it's confirmed that that really is mom, I would rather her stay away from the girls"
"Why don't you tell your sisters about this?" Leo asked.
"Because I don't want to crush their hopes. They hardly knew her, Phoebe doesn't even remember her. If I go up to them and say, hey that's not really Mom, than they'll be crushed" Prue said.
"But they could be in danger too. If it's not Patty" Leo said.
"I know" Prue said. "I'm going to go back up there, can you stay with the girls"
"Sure" Leo said.
Prue walked up to the attic. Patty, Piper, and Phoebe were sitting on the sofa in the attic.
"Did you get the girls down for a nap?" Patty asked.
"Yeah" Prue said.
"Mom, how do you know it's Darsus's son?" Prue asked.
"One of the Elder's sources say it is" Patty said.
"So, we've faced Darsus before, right?" Phoebe asked.
"Yes, um, we did" Patty said.
"Why don't you see if you can find the spell in the Book of Shadows, Mom?" Prue asked, coming up with a plan.
"But Prue we've already…" Phoebe was cut off.
"It never hurts to look twice" Prue said.
"But if you already looked there's no point in looking again"' Patty said nervously.
"We could have missed something" Prue said.
"Prue's right" Piper said. "We should look again"
Piper, Prue, and Phoebe walked to the book.
"Hey, Mom have you seen these?" Prue asked, trying to get the intruder to touch the Book of Shadows.
The fake Patty walked over to the book. Prue bumped the intruder's arm causing them to touch the book. The book shot off the stand.
"What the hell!" Piper and Phoebe yelled.
"That's not really Mom" Prue said.
"Shit!" the intruder said.
The demon shapeshifted back into itself. He resembled Darsus.
"Darsus?" Phoebe said.
"No, his son, Darien" Darien said. "Stupid witches! Now you'll just be in the way"
He threw an energy ball at Phoebe. She flew into the wall.
"Phoebe!" Piper yelled.
Piper tried to freeze him but it didn't work.
"He won't freeze!" Piper said panicking.
"He's probably immune to witches powers like Darsus" Prue said dodging an energy ball.
Piper and Prue dove behind the couch.
"We have to keep him away from Leo and the girls" Prue said.
"First we have to get to Phoebe" Piper said.
"How?" Prue said starting to panic.
All of the sudden, Prue astral projected by Phoebe.
"What the heck!" Piper exclaimed.
She looked over at Prue. Her eyes were closed.
Darsus's son tried to throw the astral projection into the wall, it didn't work. Prue's astral projection checked Phoebe's pulse. She returned to her body.
"What the hell was that?" Piper asked.
"I don't know but Phoebe barely has a pulse, we have to get her to a hospital" Prue said.
Darsus's son threw an energy ball at the couch.
"Prue, why don't you try to astral project to Leo" Piper said.
Prue closed her eyes for a few seconds.
"I can't" Prue said. "I'm going to try and make a run for it"
"I'll go with you" Piper said.
"No, I can't risk letting you get hurt" Prue said.
"Prue, I'm a big girl now. Besides, between the two of us one of us will make it"
"Okay, let's go" Prue said.
They ran towards the door. Darien was about to hit Prue with an energy ball when Piper shoved her out of the way.
"Piper!" Prue yelled.
She kept running for the door. Darien shimmered in front of her.
"Stop or I'll kill your sisters, and then your daughters" Darien said.
"What do you want?" Prue asked.
"My revenge" Darien said. "You killed my father, you and your sisters"
"Then why don't you just kill us now?" Prue said.
"Cause I want you to suffer" Darien said.
Prue tried to shove past him. He grabbed her by her throat.
"Do you really want me to kill your daughters" Darien said.
Just then Leo orbed in.
"Move and she dies" Darien said holding an energy ball in his hand.
"Heal Piper and Phoebe. Then protect the girls" Prue said.
"The girls are already safe" Leo said.
"Shut up!" Darien said. "We're leaving now"
Darien shimmered out, taking Prue with him.
Leo ran over to Piper and healed her. Then he healed Phoebe.
"Leo?" Piper said. "How did you heal us?"
"They gave me my wings back. We have a problem. Darien took Prue"
"Oh great, he didn't get to the girls, did he?" Phoebe asked.
"No, I orbed them up there. Last I knew they were with Andy and your Mom"
"Can you sense Prue?" Piper asked.
"No, she's probably in the underworld" Leo said.
"You know didn't we just rescue her from there" Phoebe said.
"Yeah, by the time all this over, we're going to know the place like the back of our hand" Piper said.
"Back to finding Prue, Leo can you orb us down there?" Phoebe said.
"I'm not supposed" Leo said.
"Well that hasn't stopped us before" Phoebe said. "Once we're in the underworld, you'll be able to sense her, right?"
"Yes" Leo said.
"Alright lets get a spell and some potions and then lets go" Piper said.
Darien shimmered into the underworld.
"My sisters will be here to vanquish you" Prue said.
"That's what I'm planning on" Darien said. "See you may have vanquished my father, but I learned from his mistake"
"What do you mean?" Prue asked.
"I have a little surprise for your sisters" Darien said. "When they try to vanquish me, they'll kill you too. Now let's wait for your sisters. Oh and don't bother to try to astral project. It won't work in here"
Prue grabbed a rock from behind her. She threw it at Darien. He ducked.
"You're going to get in my way aren't you? Well I won't let you" Darien said.
He threw the rock back at Prue, knocking her unconscious.
"Guards!" Darien shouted. "Take her to the Triad. Tell them if I die…kill her"