Recruiting the Wizard (Harry Potter/Percy Jackson)

V - PERCY - Secret Cave

The exact words I needed to hear. Banished. Annabeth, Jason and Leo looked over at me from the skies, being held up my the power of the water.
"Smell you later, Mr Not-Really-A-God!" I shot at Dionysus, as using the last of my power, I lifted myself up on a huge tidal wave, up to the rest of my friends. "On 3" I said.
"1" I dodged an incoming bolt from Mr. D. He was going full God on us now, but I could tell he didn't want us dead. He could have done that easily.
"2" I could hear Chiron shouting up at us, telling us that this was unreasonable, and to come down now.
"Brace yourselves, 3." Then I completely shut off my power. All the water crashed back into the lake, and we went with it.
"AIM FOR THE SEAWEED!" I roared, pointing at a piece of seaweed at the bottom of the lake. Everyone saw me, and leant towards it. Then, with whatever power I had left, I created a safe part of the lake, just above the seaweed, for us to land on. We all crashed down on it. Everyone looked kinda funny underwater, with their cheeks puffed out, holding air. Taking normal breaths, I pointed to a small corner of the lake, where nobody would see us. We swam towards it. Well, I forced the water to push us along, but Annabeth and Jason decided to swim anyway. Leo and I just sorta let the water push us. I could hear Clarisse laughing back up at camp, and I wanted to punch her so hard, but I had to be patient. Once everyone was in that corner, I created a huge bubble so we could all breathe.
"YOU IDIOT!" Jason shouted, trying to lunge for me, but I just left the bubble. He couldn't do that without the danger of drowning.
"What?" I asked.
"Jason, save it for inside. You don't want to fight Percy in his home turf." Annabeth warned, glaring at me.
"So, where's this secret cave?" Leo interrupted. I was glad he asked.
"Nico, Hazel's brother, showed it to me when he taught me how to Shadow-Travel." I explained. "The entrance takes the form of your greatest fear."
Annabeth looked concerned for half a second, but it went as soon as it had appeared. For example, I see a huge patch of quicksand at the bottom of the river, that's probably my entrance, my greatest fear being suffocation. "Everyone see it?"
Annabeth nodded, looking straight at the quicksand, but she would see something else. Jason was pointing at the entrance, stuttering.
"P,p, pi- NO!" he sobbed.
"Jason, calm down! It's just an image!" I comforted him. "Leo, you see it?"
He nodded sternly. "Okay. You just need to touch it, and it will disappear, revealing the entrance. Good luck."
I started to drift towards the quicksand, everyone following. Ever since the incident in Alaska, I had been absolutely terrified of suffocation. But I managed to reach the sand, and I tapped it with the tip of my finger. It all started to funnel out into a hole in the ground. I dived into it. As soon as I entered the strange hole, all my strength disappeared, and I started to lose consciousness. Stay awake, Percy, I kept telling myself, as I noticed an unconscious Leo drift below me. I could do this. I swam even further down, until I noticed there was no water anymore. I was lay down on the dingy, moist rock floor. Leo, Annabeth and Jason were lay next to me, but only Jason was still awake.
"That was tough, eh?" I muttered.
"You could say that again." Jason sighed, standing up. I pulled a can of pure nectar out my back pocket, and poured a bit into Annabeth and Leo's open mouths. They were awake in 10 seconds.
"So what now?" Leo asked, embarrassed that he was not strong enough to stay conscious.,
"See that symbol on the wall?" I said, pointing to a large red symbol of an eagle on the wall.
"Yeah" Jason muttered.
"That's going to show us where we need to go. Kind of like Athena's Mark." I said, watching Annabeth go pale. Suddenly, the symbol started to disappear, and it turned into a window. Through the window, I could see a huge castle surrounded in mystical trees and animals.
"Is that a Faun?" Jason asked, pointing at a Satyr through the window.
"Grover?" Annabeth and I said at the exact same time.
"Hey guys!" He said, sprinting up to the window. "Boy is it good to see you!"
"We haven't seen you in years!" I laughed, high fiving him through the window. "So, who's this new recruit?"
"This is his school! He gets to go to school in a castle!" Grover baaaaa'd.
"Name? Godly parent?" Leo asked, excited.
"Hecate, son of Hecate. Harry Potter."

A/N
Oh man! They're recruiting Harry Potter! Anyway, I'm so sorry this chapter was up so late, I was just so, so busy. I hope you don't mind. I was actually going to abandon this story, until I started receiving loads of support recently. Just to shoutout a few: 'feeloriginal', 'HanniB2003', 'ice8487' and many more. Thanks guys. I have also decided to hold a competition at the end of each chapter. If you can answer the question correctly first, you earn a shoutout!
Question 1)
What is the name of Hades' 3-headed pet dog? Good luck!