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“So, what does Cerberus look like?” Will asked as Nico led him down the last of the steps into the underworld, faintly glowing sword in one hand and Will’s fingers laced in the other.
The trek through the Doors of Orpheus was mercifully less eventful than their last journey down here together, but the hand holding was still a reassurance that everything was real this time, that they were together and everything was okay. Nico may have been on somewhat good terms with Epiales now (or as good of terms as someone could be with a demon), but he wasn’t taking any chances.
“A giant three-headed rottweiler, though he’s usually invisible until you get close so you might not see him at first.” Nico gently tugged Will towards a fallen stalactite. “Brace for shadow-travel.”
“Braced.”
Nico held onto Will tightly as he stepped into the ice cold shadow. The familiar voices swarmed him (they were always louder down here) and the harsh winds pushed against his face like they were on the drop of a rollercoaster, but it lasted only a few seconds. In no time at all, they popped out of the shadow of the wall that separated the Fields of Asphodel from the rest of Erebos - a short walk from where Cerberus guarded the entrance.
“Oooof!” Will exclaimed as he suddenly fell into Nico, almost knocking them both to the ground. He grabbed Nico’s shoulders to steady himself, and in turn Nico held him by the waist to stop him from falling.
“Are you okay?” Nico frowned as he looked up at his boyfriend. Will was paler than usual, some of his natural glow dampened, and his eyes looked unfocused and distanced as if he wasn’t quite here.
They had shadow-travelled together often enough at this point that Will had long found his sea legs (shadow legs?), and shadow-travel barely affected him anymore. The fact he was stumbling and dizzy now was… concerning.
“I’m fine. I just got light headed all of a sudden. Give me a minute.”
Nico nodded, but altered his grip so that he was supporting more of Will’s weight. They hadn’t shadow-travelled the last time they were here, and he didn’t realise it was going to negatively impact him this much. He had hoped shadow-travelling would be better for Will since it meant they wouldn’t be spending as much time walking through a place that was slowly killing him, but he failed to account for how shadow-travelling might exacerbate his symptoms.
If it came down to it, Nico would take him to his father’s palace and let him lie down in his bedroom there, but he had been hoping to avoid it today. The whole point of coming here was to give Will some happy memories of the underworld; a visit to Cerberus was a much safer bet than a visit to his father. Sure, they were on better terms now but how long was that going to last? Hades had always been so hot and cold with him, and he wasn’t ready for that pendulum to swing back in the other direction. He would take the risk for Will’s sake, but he wanted to avoid it if possible.
“Do you need your sun lamp?” Will, ever prepared, had packed it, a couple bottles of nectar, and a pack of medicinal Kitkats just in case.
Will shook his head. “I think I’m good for now. Let’s keep going.”
Will still looked pallid, but he could stand up without Nico’s help and the light had returned to his eyes which was the best they could hope for right now. They just needed to take it slow. “Come on.” Nico took his hand (more for his own comfort than anything else) and led him deeper into the Fields of Asphodel.
After a few minutes of walking, Will spoke up again. “I’ve never seen a three-headed Rottweiler before. How are the heads connected to the body?”
Nico glanced at him out of the corner of his eye. “What do you mean?”
“Like… does he have three heads attached to three separate necks? Or is it the middle head that has the neck, but the other two heads jut out of the same neck at a weird angle?” Will thought out loud. “Like if you were to put a collar on Cerberus, would you put on three collars for each head, or one collar around all three?”
“Uh… I guess three separate collars?” Nico had never thought about it before, but it didn’t surprise him at all that Will had. “Are you… making a meme?” He vaguely remembered Kayla showing him an image with dogs wearing pants in two different ways once. She had strong opinions about it.
The corner of Will’s lips curled up in that way it always did when Nico said something that made it abundantly clear he wasn’t born in this century, and hadn’t been exposed to the internet until he was fourteen. (In his defence, at least he knew what a meme was now! Austin and Kayla had made sure of that.) “You are very cute.” Will kissed his cheek. “But no, I’m genuinely asking. I’ve always wondered how his biology works. Have you seen his skeleton?”
“I only see skeletons of the dead, and monsters don’t die in a way that leaves skeletons behind.”
Although now that Nico thought about it, has Cerberus ever died? He assumed he would come back to life like every other monster, but Cerberus wasn’t exactly a normal hellhound. He would have to ask his father the next time they talked.
“Good point.”
“Can’t you see skeletons with your powers…?”
“Kind of, but not really. I just sort of sense when a bone is broken just by touching someone.” He squeezed Nico’s hand in demonstration. “I don’t get a clear mental image of their entire skeleton - which is a shame because I really want to know what Cerberus’s musculoskeletal system looks like. Where are his traps located? Does he have three spines? Or is it one spine and the other two heads are separate somehow?”
“It would have to be three spines, wouldn't it? Otherwise he wouldn't be able to hold up the other two heads.” Nico liked to think he had a good understanding of how bones fit together (maybe even better than Will which was saying something considering his encyclopaedic knowledge of biology, both human and not), but even he was struggling to picture how the additional heads fit with the anatomy of a normal dog.
“That's probably right, but it raises even more questions than it answers. He probably only has one spine in his back, so how do the vertebrae in the other two necks connect to it? Do they connect at all? I mean, one of the main functions of the spine is to protect the spinal cord, but if he only has one spinal cord, then the vertebrae in the outside necks wouldn’t necessarily need to connect to the main spine. Wait.” Will’s eyes widened and he turned to Nico as another thought occurred to him. “How many brains does Cerberus have? Do the heads think independently?”
Trust Will to have a mountain of questions about a three-headed dog’s biology. Then again, maybe it’s on Nico for not expecting that this playdate would involve a detailed analysis of Cerberus’s brain functionality.
“Uh… I don’t think so? I mean, they’re pretty in-sync usually. If one head’s excited, then the other two are excited too. If one barks, they all bark. I’ve never seen them fight amongst themselves or anything like that, so I think they’re all on the same page.”
“Interesting,” Will hummed in thought. “Then that either means he does only have one brain and two of the skulls are almost completely hollow, or he has three brains that all work in tandem with each other. I suppose the optic nerves in the other two heads would need to be connected to something, and connecting them to one brain in a completely different head feels like a long way for that information to travel. It would be inconvenient if his sight was asynchronous.” Will gasped. “Wait. Can he see through all six eyes?”
“Probably? The outside heads have looked at me before.”
“What about the three mouths? Does he eat with all of them?”
Now that one he knew for sure. “Yes. I brought treats for all three of them.” He pointed at his backpack. Granted, he always brought three treats because he would feel guilty if he gave attention to only one head and not the others, but if they all shared brain processes as Will was hypothesising, perhaps his guilt was unfounded.
(He was going to keep spoiling all three heads anyway.)
“Cool.” Will grinned. “But that just raises the question of how many stomachs he has. I assume just the one and all three oesophaguses - oesophagi? - connect to the same large stomach, but it would be cool if he had multiple like a cow.”
As Will rambled on about the differences between bovine and canine digestive systems, Nico couldn’t stop himself from smiling. He knew that some of the other campers found Will’s interest in biology kind of weird, but that was their loss. Will’s intelligence and his passion were two of his best traits (and it was a fierce competition), and Nico would happily listen to him talk about viscera for the rest of his life. It was a little concerning only because Will was loopy from being in the underworld and Nico got the impression that his brain-to-mouth filter wasn’t working quite as well as it usually would, but right now, it was more endearing than worrying.
Nico used to think that rambling was a bad thing. He had been conditioned to believe that from how often the people in his life would get annoyed the second the word Mythomagic left his lips, but being around Will made him realise how wrong he was. Not only was Will’s passion incredibly adorable, but he knew Will felt the exact same way about him. Will was the one person he felt like he could truly be himself around, and it was always nice to be reminded that he was that person for Will too.
It didn’t take long for them to find their way to Cerberus. Since they had entered through the Doors of Orpheus, they were approaching him from behind. Cerberus sat at attention at the gates into the Fields, all three heads staring diligently ahead at the lines of spirits coming in.
“Wait, I thought you said he would be invisible at first?” Will asked, confused.
“I guess that only applies when you approach him from the other side of the gates,” Nico mused. “It’s only the living that can’t see Cerberus. The dead can see him just fine.”
“Am I dead right now?” Will exclaimed, alarmed. Maybe Nico should have explained this to him earlier.
“No, but you’re in the Fields of Asphodel so as far as the laws governing the underworld are concerned….”
“Oh. That’s… good to know.”
“You’ll be fine. You’re with me. As long as you don’t eat any pomegranates, I can get you out. Now, come on. Let’s go say hello.”
Nico tugged Will over to Cerberus, but they didn’t have to get close for him to notice them. All six ears perked up at the sound of voices, and he turned around to check out the intruders. Once he realised it was Nico, the guard dog persona was immediately dropped and he leaped up in excitement.
His father was none too pleased that Cerberus had begun to associate Nico with treats and playtime. As a working dog, he was not to be distracted from his very important job. However, unlike guide dogs, there was never a time when Cerberus was off duty. He didn't get a break like a normal dog, so Nico was having trouble seeing the harm in coming down here occasionally - sometimes with Mrs O’Leary, sometimes without - to play with him for a little while. He needed the enrichment, and Nico doubted he was getting any from his father.
Cerberus bounded towards them, but thankfully remembered his training and didn't try to tackle Nico this time. He lay down in front of them, heads bowed in search of pets, his tail slapping against the rock as it wagged.
“Good boy.” Nico stretched up to scratch Cerberus’s middle head. (The worst part about being short was that he could only reach one head at a time, and had to stand on his tiptoes to reach his ears.)
Will hung back, stars in his eyes. “Di Immortales, he’s so much bigger than I thought he was going to be.” His fingers were twitching from the desperation to give Cerberus attention, but he was (wisely) holding himself back. “Can I pet him?”
“Let him smell you first.”
Will carefully stepped forward, palm outstretched towards Cerberus’s right head. Cerberus perked up at the unfamiliar presence, and sniffed Will’s hand. Nico held his breath as he watched them, holding on to Cerberus’s middle head just in case (not that his strength was any match for a twenty feet tall hellhound).
Cerberus let out a low growl, and Will immediately stepped back and Nico pushed himself between them.
“I think he senses you’re not supposed to be here,” Nico said, keeping an eye on Cerberus to make sure he wasn’t going to lunge at Will, but he stayed put. It seemed that Nico had built up enough of a relationship with Cerberus that he trusted his judgement of character.
“Well, I guess that’s relieving in a strange way. It would be worse if he thought I did belong here,” Will said, audibly disappointed.
Now that won’t do.
“Here.” Nico shrugged off his jacket. “Take this. Maybe if he smells me on you, he’ll know you’re a friend.”
Will visibly perked up. “Oh, if I had known that was going to help, I would have made you cuddle me before we left.”
Nico rolled his eyes, but his smile betrayed his amusement. “Just put this on, you dork.”
The jacket was a tight fit on Will and Nico was a little worried he would tear the back if he moved the wrong way, but it would have to do for now. In turn, Nico pulled on Will’s hoodie - excitingly oversized on him - and let himself bask in the comforting scent of his boyfriend. (Even if this didn’t work, at least he found an excuse to wear his boyfriend’s clothes.)
Now donning Nico’s jacket, Will slowly stepped towards Cerberus again, palm outstretched. Cerberus watched him carefully, and sniffed his hand again. The mixing of both of their scents seemed to confuse him at first, but he soon accepted Will’s presence and laid his heads back down for attention.
“Oh! It worked!” Will exclaimed and wasted no time in petting Cerberus’s rightmost head. “You’re such a good boy, aren’t you? I can’t be mad at you for trying to scare me off when you were just doing your job, weren’t you?”
As Will cooed and fawned over Cerberus’s rightmost head, Nico moved over to let the leftmost head. It wasn’t the first time Nico had heard Will talk in a baby voice to a dog - he spoke to Mrs O’Leary the same way - but it warmed his heart to see him do it with Cerberus. Considering how Will felt about the underworld until somewhat recently, it was nice to see him make a genuine effort to connect with a part of it.
“I think our theory about Cerberus having three brains was right,” Will said after a few minutes.
“Yeah?”
“Yeah. They’re not completely independent - the heads aren’t fighting for attention the way three individual dogs would - but they are acting independently to some degree. Only one of the heads tried to sniff my hand.”
“Are three brains possible?”
Will shrugged. “Sure. Octopods have nine brains - one in the head, and one in each tentacle. Or at least, they have nine of what we would think of as brains. If I had to guess, I would say Cerberus’s middle head has a normal dog brain that controls everything a normal dog brain would, and then the other two brains only control each individual head. I’m not ruling out the possibility that he only has one brain, but it feels weird to me that he would have three heads but only one brain.”
“He is a mythical creature though. A lot of things in our world operate outside the laws of science,” Nico pointed out (but if Will had theories for how their powers worked scientifically, then he definitely wanted to hear them.)
“True, but I refuse to believe everything is magic. There must be some explanation behind how such a good boy functions,” Will cooed the last part, and Cerberus panted and wagged his tail at the attention. Whatever reservations he had against Will were gone now that he was giving him so much affection.
“And maybe that explanation is magic.”
“Agree to disagree,” Will huffed, and Nico smiled to himself but let the argument drop. He was only pushing that option to rile Will up anyway.
“So what’s the verdict on the spine situation then?”
“Hard to tell without an x-ray unfortunately, but I did figure out where his traps are though! They’re right here.” Will reached around Cerberus’s head to pet a muscle slightly behind his rightmost head. (Yet another reason to be jealous of his boyfriend’s height. He could reach Cerberus just fine.)
“Well, that’s something.”
As they talked, Cerberus suddenly pushed up and out of their grip. He ran around to the other side of the wall, and returned a few seconds later with a large red ball in his centre mouth.
“He has toys?!” Will lit up with excitement.
Nico nodded. “I’ve snuck a few down here over the years. This one was a gift from Annabeth.”
Cerberus dropped the ball at Nico’s feet, but Nico gave it to Will to throw. He could play with Cerberus anytime; this was Will’s moment. “Do you wanna play fetch?”
“Yes!” Will took the ball from him as if Nico had just handed him a million dollars. “Where do I throw it? In the Fields? Out the gate?”
“Anywhere’s fine, just make sure you throw it hard. He’s a big boy, he can run far.”
Will nodded, and proceeded to hurl the ball as far as he could into the Fields of Asphodel. Cerberus darted after the ball like a shot, running so fast and suddenly that he almost knocked them over. He skidded along the rock, kicking up dust as he went. The first head snapped at the ball, missed, and then the second one grabbed it. Ball secured in his jaw, Cerberus bounded back to Will and dropped the ball at his feet.
Wil picked it up, eyes shining with glee, and not the least bit bothered by how the ball was dripping with slobber. “This is the best day of my life,” he announced, and threw the ball again.
Nico was content to watch as Will played with Cerberus, only taking over when Will needed a break. It wasn’t long until they had exhausted Cerberus enough that he was happy to lie down on the ground and let them rub his belly as they rested against him.
Will had stopped rambling a little while ago, and had taken to humming one of his Mom’s songs - a sign that the underworld was taking its toll on him.
“You okay?” Nico asked, and lightly bumped against his shoulder.
“Yeah, I’m just tired,” Will explained softly with a drained smile. His skin had grown more pallid and waxy, and his golden curls had lost some of their bounce. The only reason Nico wasn’t forcing him to drink some nectar was how utterly content he looked despite it all.
“Let’s give Cerberus his treats and head back.”
Nico climbed to his feet, and then took Will’s hands to help him up too. Will swayed on his feet for a second, but Nico held him until he found his footing. Once he was stable, Nico unzipped his backpack and handed Will a full rotisserie chicken. (He tried giving Cerberus a full bag of dry dog food once, but the logistics behind getting him to eat all of the biscuits and not the plastic bag put him off trying that again. The chickens were much easier, and the bones were thankfully too small to lodge in his throats.)
“You feed the right head, and I’ll get the others. Watch the teeth.”
Will waited until Nico had tossed the first chicken into the centre head’s mouth before he did the same with the right. Nico then fed the third head, and once Cerberus was happily chewing, he stepped forward to pet him one last time. “You should go back to work now, but I’ll be back soon, okay? Good boy.”
Cerberus licked Nico’s entire head, and then trotted off to return to his post. Nico turned back to Will only to catch him staring at him with so much adoration in his face that it knocked the breath from his lungs.
“What?”
Will shrugged, shameless. “I like watching you be kind to animals. It’s sweet.”
Nico felt his face flush. It was funny; after being together for a year, he thought Will’s words wouldn’t have this effect on him anymore, and yet here they were. (He secretly hoped they never stopped.) “So are you.”
“It’s cuter when you do it.”
“You have never been more wrong.”
Will grinned. “Agree to disagree.”
Nico rolled his eyes affectionately, and took Will’s hand. “Do you think you can manage shadow-travelling back? Or would you prefer to walk?” He wasn’t sure which would be better when Will was so drained, but he trusted Will to know his limits.
“I think I can do shadow-travelling, but maybe after we can sit on the bottom of the steps and rest for a while before we go up? We still have those Kitkats to eat too.”
Nico gave his hand a squeeze. “Sounds good.”
As they made their way back towards the wall, Will asked, “Can we come back to see him again? I mean, I still have so many questions about his anatomy that need answering, so we should probably conduct more experiments. You know, for science.”
“Right. For science.” Nico matched Will’s faux serious tone. “We can come back whenever you want.”
“Cool.” Will beamed, and then leaned in for a quick kiss.
Nico was quietly buzzing. Will loved Cerberus and wanted to come back. They may not have figured out what all of Cerberus’s internal biology looked like, but he did give Will a reason to enjoy the underworld and that made this visit a roaring success.
He gave Will's hand another squeeze, and led him into a shadow to begin the journey home.