Everything had changed: The Magic of the Sea was lost after Henry Turner had destroyed Poseidon's Trident. Captain Hector Barbossa, as well as the Pirate Hunter Salazar, were gone. All the myths were disenchanted. And a special connection was severed:
The link the Trident had been maintaining between the sea and its lord.

Lord Poseidon, God of the Sea, Storms, Earthquakes, Droughts, Floods and Horses, the Earthshaker, the Stormbringer, Father of Horses and King of Atlantis, sat in his throne in his already mentioned kingdom, that was still under reconstruction. And as if the still outstanding construction works were not bad enough, he had a problem and was consequential somewhere between the devil and the deep blue sea.
The devil in this analogy would be his brother Zeus, who would be less than pleased if he had to tell him about his little secret. But the deep blue sea was much worse. If she knew about the destruction of the Trident, his wife, Amphitrite, would start nagging him and tell him to find a solution. And the only possible answer he could think of was sending Percy to his Mirror-Dimension to reconnect him to the dimensions oceans, which was like a secret energy-reservoir.
But, and here he was at his old problem, he could not send Percy there, or Zeus would learn of the dimension and not sending Percy there would result in Amphitrite finding out about it either way.
Either she would notice his weaker state, or Amphirite would hear about it another way. At the latest, when Zeus was inevitably complaining about Percy's disappearance. And that was not even considering what Percy would say about it. The array of possible answers ranged from,
"I just finished a war and got home," over,
"I don't really care," to,
"That would be fun."
Poseidon could not imagine which reaction he would receive. That was also a tad bit concerning.

Obviously, the troubling thoughts were written in his face, or Triton would not have addressed him the way he did:
"Father?" He asked, "Is there something that is bothering you?"
"There is, but it's nothing you need to concern yourself with."
"What is it, father?" Triton asked, exasperated, "I only want to help you."

"Do I really look that bad, eh?" Poseidon inquired, amused.
"You look still exhausted from the war and your Roman-Greek Schizophrenia. Although there's something other, too. Something that I can't place."

This time Poseidon's sigh sounded defeated.
"Swear not to let your mother know, and help me hide it, and I'll tell you."
"I swear, Father."

Poseidon smiled knowingly, a little twinkle in his eyes.
"On the Styx, Triton. On the Styx."
"I solemnly swear on the Styx that I won't inform Mother of anything you're about to tell me." He paused shortly and then added, "but you know that won't keep mother from finding out herself whatever it is you are hiding from her."

Poseidon smirked. "No, I know that, but well, I need your help because my only idea would be too conspicuous to do."
"Slow down, Father. Tell me one thing after another."
"You know before the seas were polluted with diesel, plastic and the such?" Nostalgia was all over the King's demeanour.

Triton nodded in response.
"Well, I thought that this time was, despite its bloodiness, beautiful. And I decided to create a reflection to this time and this Reflection – Dimension … it gave me more energy than I needed to maintain it."

"You did what?" Triton was shocked, "If Zeus knew that, you could repeat what caused you to be forced to build the walls of Troy! But you used past time, not present. So what exactly happened?"

"That's why I wanted no one to find out. Your uncle can be as annoying as they come about things like this. So for your understanding, I had an anchor there." Poseidon started to explain. "It sent the energy that the reverence and the fear of the sea created to me, which strengthened me. My problem now is that this anchor, a trident, has been destroyed. And I need someone to place another trident in the dimension in a way that the least people possible find out about it."

Suddenly, Triton's demeanour changed to cold and closed-off.
"You're planning on sending your bastard."
"Triton," Poseidon exclaimed, horrified, "he is your brother and one of the greatest heroes ever to live, and he never even disrespected you. If you are angry about his birth, direct that anger to me, not Percy. He is the most innocent in all of this."

Triton scoffed. "Innocent? That's not how I heard it. Did you know he can control poison and the Rivers of the Underworld?"

"And that does surprise you?" Poseidon asked, disbelieving, "the only reason you and me can't control them is they are mainly another's realm, so to speak. Hades and I – and in some circumstances, Ares – have been fighting over those who died at sea for millennia, so Hades is extremely picky over domain rights with me. I couldn't gain access to the underworld without his consent. Further, the deities of the Rivers would not take too kindly to bending their domain. But Percy is the one person who can challenge that. He isn't restricted by the ancient laws. He and his powers are only limited by his imagination of them.
That's another reason I want him to do it. It could help to better grasp his powers and their limits without doing too much damage here."
Poseidon looked at his heir in hopes of achieving a consensus.

AN:

So, I couldn't really finish any of the chapters of my other stories for Christmas that's why I just superficially edited this story's beginning that I have been sitting on for at least one to two years. It's a small present, I know, but here you have it.

Merry Christmas, Happy Holidays and whatever else you guys celebrate.

I won't make promises on updates for my other stories, except that there will be some, hopefully, even relatively soon.
If you have questions or want to chat (when I find the time), you can find me on the discord server The Emerald Library (permanent invite: discord:gg-bBdr9FYaHH just change : to . and - to /)