River Styx

"Ms. Jackson," Nico said, "Percy needs your blessing. The process has to start that way. I wasn't sure until we met Luke's mom, but now I'm positive. This has only been done successfully twice before. Both times, the mother had to give her blessing. She had to be willing to let her son take the risk."

Percy," she said, "I give you my blessing."
I didn't feel any different. No magic glow lit the kitchen or anything.
I glanced at Nico.
He looked more anxious than ever, but he nodded. "It's time."

TLO ch.6

Then again, Luke had been here, and he hadn't turned back.
That's why Luke had been able to host the spirit of Kronos without his body disintegrating. This is how he'd prepared himself, and why he seemed impossible to kill. He had bathed in the River Styx and taken on the powers of the greatest mortal hero, Achilles. He was invincible.
"I have to," I said. "Otherwise I don't stand a chance."
Achilles lowered his head. "Let the gods witness I tried. Hero, if you must do this, concentrate on your mortal point. Imagine one spot of your body that will remain vulnerable. This is the point where your soul will anchor your body to the world. It will be your greatest weakness, but also your only hope. No man may be completely invulnerable. Lose sight of what keeps you mortal, and the River Styx will bum you to ashes. You will cease to exist."

Before I could change my mind, I concentrated on the small of my back — a tiny point just opposite my navel. It was well defended when I wore my armor. It would be hard to hit by accident, and few enemies would aim for it on purpose. No place was perfect, but this seemed right to me, and a lot more dignified than, like, my armpit or something.
I pictured a string, a bungee cord connecting me to the world from the small of my back. And I stepped into the river.
Imagine jumping into a pit of boiling acid. Now multiply that pain times fifty. You still won't be close to understanding what it felt like to swim in the Styx. I planned to walk in slow and courageous like a real hero. As soon as the water touched my legs, my muscles turned to jelly and I fell face-first into the current.
I submerged completely. For the first time in my life, I couldn't breathe underwater. I finally understood the panic of drowning. Every nerve in my body burned. I was dissolving in the water. I saw faces — Rachel, Grover, Tyson, my mother — but they faded as soon as they appeared.
"Percy," my mom said. "I give you my blessing."
"Be safe, brother!" Tyson pleaded.
"Enchiladas!" Grover said. I wasn't sure where that came from, but it didn't seem to help much.
I was losing the fight. The pain was too much. My hands and feet were melting into the water, my soul was being ripped from my body. I couldn't remember who I was. The pain of Kronos's scythe had been nothing compared to this.
The cord, a familiar voice said. Remember your lifeline, dummy!
Suddenly there was a tug in my lower back. The current pulled at me, but it wasn't carrying me away anymore. I imagined the string in my back keeping me tied to the shore.
"Hold on, Seaweed Brain." It was Annabeth's voice, much clearer now. "You're not getting away from me that easily."
The cord strengthened.
I could see Annabeth now — standing barefoot above me on the canoe lake pier. I'd fallen out of my canoe. That was it. She was reaching out her hand to haul me up, and she was trying not to laugh. She wore her orange camp T-shirt and jeans. Her hair was tucked up in her Yankees cap, which was strange because that should have made her invisible.
"You are such an idiot sometimes." She smiled. "Come on. Take my hand."
Memories came flooding back to me — sharper and more colorful. I stopped dissolving. My name was Percy Jackson. I reached up and took Annabeth's hand.
Suddenly I burst out of the river. I collapsed on the sand, and Nico scrambled back in surprise.
"Are you okay?" he stammered. "Your skin. Oh, gods. You're hurt!"
My arms were bright red. I felt like every inch of my body had been broiled over a slow flame.
I looked around for Annabeth, though I knew she wasn't here. It had seemed so real.
"I'm fine ... I think." The color of my skin turned back to normal. The pain subsided. Mrs. O'Leary came up and sniffed me with concern. Apparently I smelled really interesting.

TLO ch.8