Arai curses

We are the arai , said that weird voice-over, like the entire forest was speaking. You cannot destroy us.
Annabeth pressed against his shoulder. “Don’t touch them,” she warned. “They’re the spirits of curses.”
“Bob doesn’t like curses,” Bob decided. The skeleton kitten Small Bob disappeared inside his coveralls. Smart cat.
The Titan swept his broom in a wide arc, forcing the spirits back, but they came in again like the tide.
We serve the bitter and the defeated, said the arai. We serve the slain who prayed for vengeance with their final breath. We have many curses to share with you.
The firewater in Percy’s stomach started crawling up his throat. He wished Tartarus had better beverage options, or maybe a tree that dispensed antacid fruit.
“T appreciate the offer,” he said. “But my mom told me not to accept curses from strangers.” The nearest demon lunged. Her claws extended like bony switchblades. Percy cut her in two, but as soon as she vaporized, the sides of his chest flared with pain. He stumbled back, clamping his hand to his rib cage. His fingers came away wet and red.
“Percy, you’re bleeding!” Annabeth cried, which was kind of obvious to him at that point. “Oh, gods, on both sides.”
It was true. The left and right hems of his tattered shirt were sticky with blood, as if a javelin had run him through.
Or an arrow... Queasiness almost knocked him over. Vengeance. A curse from the slain.
He flashed back to an encounter in Texas two years ago—a fight with a monstrous rancher who could only be killed if each of his three bodies was cut through simultaneously.

Geryon,” Percy said. “This is how I killed him....”
The spirits bared their fangs. More arai leaped from the black trees, flapping their leathery wings.
Yes, they agreed. Feel the pain you inflicted upon Geryon. So many curses have been leveled at you, Percy Jackson. Which will you die from? Choose, or we will rip you apart!

“LEFT!” PERCY DRAGGED ANNABETH, slicing through the arai to clear a path. He probably brought down a dozen curses on himself, but he didn’t feel them right away, so he kept running.
The pain in his chest flared with every step. He wove between the trees, leading Annabeth at a full sprint despite her blindness.

FOR ONE EXCITING MINUTE, Percy felt like he was winning. Riptide cut through the arai as though they were made of powdered sugar. One panicked and ran face-first into a tree. Another screeched and tried to fly away, but Percy sliced off her wings and sent her spiraling into the chasm.
Each time a demon disintegrated, Percy felt a heavier sense of dread as another curse settled on him. Some were harsh and painful: a stabbing in the gut, a burning sensation like he was being blasted by a blowtorch. Some were subtle: a chill in the blood, an uncontrollable tic in his right eye.
Seriously, who curses you with their dying breath and says: I hope your eye twitches!
Percy knew that he’d killed a lot of monsters, but he’d never really thought about it from the monsters’ point of view. Now all their pain and anger and bitterness poured over him, sapping his strength.
The arai just kept coming. For every one he cut down, six more seemed to appear.
His sword arm grew tired. His body ached, and his vision blurred. He tried to make his way toward Annabeth, but she was just out of reach, calling his name as she wandered among the demons.
As Percy blundered toward her, a demon pounced and sank its teeth into his thigh. Percy roared.
He sliced the demon to dust, but immediately fell to his knees.
His mouth burned worse than when he had swallowed the firewater of the Phlegethon. He doubled over, shuddering and retching, as a dozen fiery snakes seemed to work their way down his esophagus.
You have chosen, said the voice of the arai, the curse of Phineas...an excellent painful death.
Percy tried to speak. His tongue felt like it was being microwaved. He remembered the old blind king who had chased harpies through Portland with a WeedWacker. Percy had challenged him to a contest, and the loser had drunk a deadly vial of gorgon’s blood. Percy didn’t remember the old blind man muttering a final curse, but as Phineas dissolved and returned to the Underworld, he probably hadn’t wished Percy a long and happy life.

Now he was in Tartarus, dying from gorgon’s blood plus a dozen other agonizing curses, while he watched his girlfriend stumble around, helpless and blind and believing he’d abandoned her. He clutched his sword. His knuckles started to steam. White smoke curled off his forearms.
I won’t die like this, he thought.
Not only because it was painful and insultingly lame, but because Annabeth needed him. Once he was dead, the demons would turn their attention to her. He couldn’t leave her alone…

It took all his remaining effort, but he got to his feet. Steam rose from his whole body. His legs shook. His insides churned like a volcano.
At least Percy could go out fighting. He raised Riptide.
But before he could strike, all the arai in front of him exploded into dust.

HoH ch.30-31

| got inside his next thrust and stabbed him right through the middle chest.
‘Aghhh!’ He crumpled to his knees. | waited for him to disintegrate, the way monsters usually do. But instead he just grimaced and began to stand up. The bleeding slice through his chef’s apron started to heal.
‘Nice try, sonny,’ he said. ‘Thing is, | have three hearts. The perfect backup system.’
| jabbed Geryon in the left chest, but he only laughed. | stuck him in the right stomach. No good. | might as well have been sticking a sword in a teddy bear for all the reaction he showed.
Three hearts. The perfect backup system. Stabbing one at a time was no good...
Geryon laughed. ‘You fool! One arrow is no better than one sword.’
He raised his swords and charged. | dived sideways. Before he could turn, | shot my arrow into the side of his right chest. | heard THUMP, THUMP, THUMP, as the arrow passed clean through each of his chests and flew out his left side, embedding itself in the forehead of the grizzly bear trophy.
Geryon dropped his swords. He turned and stared at me. ‘You can’t shoot. They told me you couldn't...’
His face turned a sickly shade of green. He collapsed to his Knees and began crumbling into sand, until all that was left were three cooking aprons and an oversized pair of cowboy boots.

BotL ch.9