That night Sally is pulled into a dream as soon as she falls asleep.
The first thing she notices is that she's underwater, but she seems to be breathing perfectly fine. She takes in her surroundings and finds herself in a grand throne room. One she's visited once before in a different dream. Seated on a regal golden throne, inlaid with mother of pearl, is the lord of the ocean himself.
"Poseidon." She says, dipping her head in greeting.
Poseidon smiles, "Hello, Sally. How are you keeping?"
Sally shrugs, "As well I can I suppose, considering the state that our son is in."
The smile slips off Poseidon's face and he sighs, "Yes, that is part of the reason why I have brought you here tonight. I apologise for pulling you from your slumber."
Sally smiles tightly at the apology, he's still so charming, but she's glad to realise that his presence isn't flustering her at all tonight, as it had when he had shown up for Percy's birthday party a few years ago.
"It's alright." She amends, "As long as it seems you've brought me here to talk about Percy."
Poseidon's smile returns for a moment in reply before slipping away again. She can plainly see the worry in his sea-green eyes, which only worries her more.
"Yes, I am concerned for Perseus. Especially now that he's come into the mortal world." Poseidon says.
"What do you mean?" She asks, "What's been going on?"
Poseidon regards her for a moment before replying, "Perseus has been plagued by nightmares ever since the defeat of Gaia. I know that nightmares are common for demigods, especially one as powerful as Percy, but these dreams… They're different. I was able to shield him from them to a certain extent while he was at camp, make them less intense. However, now that he's come into the mortal world, I am finding it difficult to keep shielding him. It's almost as if someone is fighting me. Someone very powerful."
Sally iss horrified, "Poseidon, who would do that? Who would be powerful enough to resist your power?"
Poseidon grimaces, "Unfortunately the answer to your first question is a lengthy list. The list that answers your second answer is notably shorter. There's a presence, though, one which I have not encountered in many centuries."
"Then you know who's causing this?" Sally asks.
"I am not certain, but the presence feels an awful lot like Tartarus." Poseidon answers gravely.
Sally only stares at him in shock.
"As I said, I am not certain, but the fact that the presence feels like him, combined with the fact that all the dreams have been about Percy's time in Tartarus only serves to strengthen my theory."
"Is there nothing you can do to stop him?" Sally asks in a small voice, feeling absolutely helpless.
"I am working on something." Poseidon answers, "But I have not only brought you here to inform you of my suspicions. I also brought you here because Percy is currently stuck in a nightmare that I can't seem to pull him out of and I think you might be able to help."
Sally doesn't understand, "What can I do to help if even you can't pull him out of it?"
Poseidon smiles at her, "Never underestimate the power of a mother, my dear." He says as he holds his hand out to her.
Sally hesitates for only a second before reaching out and taking his hand.
In the next instant they are engulfed in darkness. The coolness of the ocean on her skin is replaced by an almost unbearable heat and the smell of death. For a moment she is gripped by panic but then Poseidon squeezes her hand reassuringly and she realises that she can make out his figure in the darkness beside her.
"Where are we?" she asks, her voice barely above a whisper.
"Tartarus." Poseidon answers grimly, his voice only marginally louder than her own. "Look."
She sees that Poseidon is pointing at something and looks in that direction. He's pointing to the only illuminated area and the sight she is greeted with brings her to tears.
There, wondering precariously close to the edge of a cliff is Annabeth. She's bruised and bloody. She's crying out for Percy, stumbling around with her hands held out in front of her as if she can't see. Sally frantically searches for Percy. Finally her eyes land on a hunched over figure surrounded by a swarm of black creatures. He has riptide held out in front of him, trying to fight the black swarm off. He looks absolutely drained and Sally knows with terrifying certainty that somehow he's been mortally wounded. She's watching her son die.
"Poseidon, he's dying! You have to do something!" Sally screeches.
"I am already doing all that I can, Sally." Poseidon answers and suddenly she can hear the strain in his voice, "It's up to you now. Call to him, let him know you're here and that he's not alone."
Sally nods, determination welling up inside her chest. She was going to save her son from this terrible nightmare.
"Percy!" She calls, moving closer to him as fast as she can while stretching out her hand to him, "Percy it's me! It's mom! I'm here, you're not alone! I'm here."
She keeps calling to him, repeating herself over and over until she's practically right next to him. Now that she's closer she can hear all the horrible things that the horrific black creatures are whispering to Percy. They're telling him that he's weak, he's useless, and that he'll never be able to save his friends. Their whispering voices infuriate Sally. She wants to turn on them and tear them apart herself but she knows that won't help. She needs to get Percy's attention. So she leans down until her mouth is almost at his ear and shouts: "Percy!"
Suddenly Percy looks up, whipping his head around, his gaze searching, "Mom?"
His voice comes out in a whine. He sounds so lost, so broken, it breaks Sally's heart into a million pieces but she calls out to him again.
"I'm here Percy! I'm right here!"
Finally he turns his head toward her and it seems like he can finally see her.
She gets her first clear glimpse of his haggard, tear-streaked face and feels her heart breaking even more.
"Mom?" he asks again, in the same whining tone, as if he's in a lot of pain and he can't take it much longer.
"I'm here, sweetie." She says, reaching her hand out to him, "Take my hand, we can get out of here."
He hesitates, "Annabeth…"
"She's fine, sweetie. This is just a dream. None of it's real. Just take my hand and we'll leave this place."
He hesitates for a second longer before grasping her hand.
As soon as he has it she feels Poseidon pulling her back. The transition from dark to light isn't as sudden as it had been to from light to dark. She can feel Poseidon pulling them with all his strength, as if he was caught in a tug of war and she and Percy were the rope. She pulls Percy in close to her and holds onto him with all her strength, determined not to lose him to the darkness again.