Brothers from another mother - A Hades and Percy Jackson crossover

Chapter 9 - Dear hydra

As soon as they stepped off of the boat and into the next chamber, Zagreus's arm shot out, stopping the demigods from going any further. They both jolted in surprise, and Will looked like he was about to protest.

But then he saw the hydra.

'Holy- what is that?'

'That is the remains of the monster slain by... I think his name was Heracles? The Lernaean Hydra. But- not to brag- we're totally best friends. So I call him Lernie.'

Nico raised an eyebrow.

'So that's what you were talking about. I can't believe you gave a nickname to such a dangerous creature. I mean, you are a god, so I guess this isn't a massive thing for you, but...'

'Ah, it's fine. He likes it. Anyway... this is the final chamber we have to fight through before we can go to Elysium. A lot more predictable than Meg... see the colour of the horns?'

'Uh, yeah. They're green. What does that have to do with anything?'

'I don't think the Codex mentions the different variant, so I'll explain it to you. I'm going to assume that you both know its normal attacks from reading the entry, right? And about the support heads later on.'

They nodded.

'Okay, good. This is a pretty easy version of Lernie to deal with, so you two should be mostly fine. The only things you need to watch out for with this one is the fact that it had two new attacks. One - he spits out these weird spiky grey ball things. After a short amount of time, they'll explode and summon a Bloodless Bone-Raker. As soon as you spot one of those, destroy them. They also summon one if it lands on your head, which I found out the hard way...'

He trailed off, before shaking his head and returning to his prior explanation of the dangers.

'and two, if you see a shadow appear above your head, run. I mean it. They're called Skull-Crushers, and as the name implies, you will be crushed. I'm okay with them, but you're mortals, and you will maybe probably definitely die if one of them lands on you. So, uh, don't get hit. Please.'

Will looked mildly alarmed at that, but then also shook his head and nodded, indicating that he was ready. Nico straightened up, and Zagreus moved his arm away from them. It was perfect timing, too, because Lernie noticed them in that moment. A deafening roar echoed through the cavern, causing a few stalactites to go plummeting into the lava below. Zagreus winced as some of it splashed onto his back.

'Good to see you too, Lernie! It's been a while.' 

He dashed forward, striking at the side of the hydra's head with the Twin Fists and causing it to go reeling to one side. The demigods stayed back for now - Lernie was floating above the lava, after all, and mortals and fire didn't exactly mix well. After recovering, it tilted its head back, making a sort of hacking noise a bit like a cat about to spit up a hairball. Then a spiky ball came flying from its mouth, landing with a loud thud on the ground right next to Nico. 

'Ah!'

He jumped, spinning around to face it. Will shot at the orb, but the arrow just bounced uselessly off of its surface. Nico unsheathed his sword, plunging it into the very top. The outsides peeled off, a strange goopy substance coming out of the inside and getting on the weapon, and a small heap of bones clattered out before turning to dust. The demigod made a face of mild disgust, shaking his sword to get the ooze off. 

'Gross.'

They made a good team, Zagreus going for Lernie, Nico stabbing the balls before they could summon the monsters, and Will sniping any that managed to hatch. Then came the second phase.

The hydra drew its head back, hissing furiously. A sort of shimmer came over the air around it, and Zagreus's attacks were rendered nugatory. He growled in frustration, looking over his shoulder at the demigods.

'You two! This is the most dangerous part. It happens twice. Will, if you can, try and shoot one of the heads. Nico, I don't want you getting close to the lava, so just back him up against any attacks and keep destroying the balls. Let's not waste time.'

Nico gave a shout of affirmation to show that he had heard him, Will following suit. They went to tackle the support head in the far left corner, while the god made his way over to the one next to them to hopefully prevent it from attacking them. He was much more efficient at destroying them than the mortals were - to be fair, arrows probably weren't going to do much against a bone hydra with massive gaps in its head and spine, but they were managing - and soon, all the support heads were gone. Lernie lost the shimmer, and his attacks worked again.  

They repeated the process from before until the second phase, which only lasted slightly longer than the first. But as Zagreus went to strike the hydra again, he was stopped in his tracks by a cry that most definitely did not sound like a monster.

Shit. Which one of them was it?

He whipped around to see Will on the ground, the lower part of his leg trapped under one of the balls. He obviously hadn't been able to get out of the way in time, and he looked like he was in a lot of pain. Nico was next to him in a flash, stabbing the ball with far more force than necessary with rage glinting in his eyes.

'Stupid bloody hydra! Will, are you okay? Is it broken?'

'I- I don't- maybe- I can't move it...'

Zag, who had been watching them in concern, had also neglected to think about the massive hydra behind him and was suddenly hit with force from behind. Its jaws closed around his arm, and he cursed as he was dragged off of his feet and then thrown to the ground. Pain flared through his forearm, but he pushed through it and got up.

'You two! Are you okay?'

Will winced when he tried to move his leg, and it was clear that he was fighting back tears.

'I'm- I'm okay- just get the hydra-'

Hesitating for a second before turning back around, he dealt the finishing blow, and Lernie's bones crumbled into the lava. After hastily picking up the diamond, Zagreus rushed over to them. He looked at Nico. 

'Come on. Get him on my back. The next chamber has a fountain.'

Nico was fiddling anxiously with a small coin. As soon as Zagreus gave him the instructions, he complied, hoisting his boyfriend up as gently as he could. Will let out a little noise of pain.

'Ah-'

The air was tense as they road the raft to the chamber that separated Asphodel and Elysium. Will's breathing was labored. His leg had started bleeding, which shouldn't have happened... the skin hadn't been broken. Nico still fiddled with his coin, and Zagreus gave him a what he hoped was a reassuring glance.

 'Don't worry. He'll be okay.'

Art by u/blubgy on Reddit! (the watermark, beeho1der, is their Twitter)