I feel its worth noting after a conversation I had about this - I am not trying to make serial killers sympathetic. I'm just playing with a dynamic, and Hiccup has a back story like pretty much every serial killer there is.

Don't love how this chapter came out in parts, but I'm hoping it does enough with backstory that more present/future stuff makes sense? Idk.

Current upload schedule is when I have a four-chapter buffer. That way if I can't work on Serialcup for a while, I have a months worth of weekly updates. I just finished Ch7, so here's Ch3.

-HTTYD-

Hiccup wiped his face on his sleeve, repressing the urge to spit the blood out of his mouth. Even with a helmet, it managed to get everywhere. But spit contained DNA, and Hiccup wasn't that stupid. Glancing around one last time, he dropped to one knee, ignoring the ache in his leg as he pulled out the little pocket blowtorch - artists got all the cool stuff, he laughed to himself. The body on the ground hadn't moved for a while, but Hiccups compulsion to brand them was an excellent way to be certain.

He put the knife back in its padded carry pouch, tucked it into the compartment of his leg. He only wore the 'full leg' shaped one when he was hunting, and his less 'realistic' cup-and-pylon style leg the rest of the time. It wasn't like Hiccup ever wore shorts outside his home, so nobody saw what kind of prosthetic he had on.

The ring was far too big for his slender hands, but it meant he could slip the band over a gloved finger with ease. He heated the ring until it glowed the ring colour, scalding to the touch. Probably. Hiccup had invested a chunk of money into high quality gloves that would protect his hands from heat and blood and sharp blades, while still affording him the flexibility to wield a weapon. Sometimes one of opportunity, but he always carried a knife. The knife. The knife he'd pulled out of his dead stepfather. His mother told him to throw it out. Hiccup couldn't. He'd cleaned it, bleached just like everything they couldn't bury or burn.

Hiccup found a patch of skin not covered in blood or bruises or swelling, pressed the glowing ring to it. He let out a breath as skin crackled and hissed, the weight of childhood fear leaving him for just a moment. He'd been planning to wait a little longer, even though the urge was back. But then Astrid asked about bloodstains and wool... it set him off. Turned urge to need. So Hiccup scoured his little prey list, adding up the routines he'd tracked until he found one who would be out at night.

Sometimes he found them by chance, prowling 'bad' areas to keep his pattern unpredictable. Other times he dug through police records for domestic abusers, rapists... those who got away, intimidating victims out of testifying. Hiccup had been too afraid once. If he was going to answer the urge to take lives, he'd figured he might as well save others from fear.

Hiccup even trawled the Darknet sometimes - it was a good place to find out who knew what. He was talked about there, but none of the 'information' he saw exchanged about him was really identifying. Hacking was a hobby, a byproduct of hours holed up with a computer while Hiccup was recovering from countless injuries inflicted by Alvin, the tech a gift from his grandmother - Alvin didn't take it because he didn't want close attention paid. He smashed up just about everything else Hiccup owned, but he was trying to keep Stoick's mother pacified so she wouldn't get suspicious. She had Stoick's life insurance money, after all, set up in a trust for Hiccup to get when he turned eighteen. It wasn't much, but it was enough for his stepfather to keep Hiccup alive.

A decision he'd likely regret. If he was still alive to do so.

Watching the brand settle in the moonlight, Hiccup made sure he hadn't left anything. Zipped his jacket up. Then he went home. Pulled off the thick wool jumper he'd worn for the occasion, surveying it with a knowing eye. Wool wasn't his favourite, but Astrid had asked after all.

Valka found him in the garden, post-shower, dressed in pyjamas and watching his jumper soak in cold water. Hot water made stains set.

"Again son? I thought you were cutting down."

"It was for research. And itchy fingers. I left my phone at home, don't worry."

After his first - Alvin - Valka helped him clean up and hide the body. Maternal protection hadn't ended there. She was the only one he could talk to about it, and she made sure Hiccup did everything he could not to get caught. Up to and including giving Hiccup an alibi once - someone caught a glimpse, just one, of a skinny guy in a beanie hat bent over the body in an alleyway. And while Hiccup hadn't been a suspect, he had been asked in for a line-up by pure chance - he was just out picking up Valka's prescriptions. And when the stranger IDed him, his mother gave a heartfelt assurance that Hiccup had been with her the whole night, bringing her water when new medication had made her sick.

It worked.

He started wearing a helmet after that. A custom job, one he made himself. No trail that way.

"Research?"

"I'd never worn wool before. Curious about stain removal."

The knife and the ring both sat in a strong cleaning solution, removing blood and skin and DNA. His mother shook her head, but got herself a cup of tea and came to sit outside with him. Hiccup got her a fleece throw when he saw her shiver. Neither of them commonly slept through the night, plagued by pain and nightmares and residual insomnia from a time where sleep was just a more vulnerable moment.

"Who was it tonight?"

"Guy who beat his boyfriend black and blue, but the cops didn't take it seriously because they're gay."

If he knew which one made that call, Hiccup would have added them to his list too. Satisfied the stain was as treated as it would get in the bucket, Hiccup dumped it in the washing machine and set the cycle, tossed a little bleach in the bucket to help stop the blood from staining and rinsed it out before he went back to the garden, stretching out on his lounger and rubbing his knee with a groan.

"Bad?"

"Not really. More irritated I've been on it a while. Once we finish these we should go to bed."

Once he'd seen his mother back to her room, Hiccup pulled the jumper out of the machine. He saw no stains, so the usual methods he used seemed to have worked pretty well. He tapped out the reply to Astrid as he headed to his room, dropping into his bed with a sigh of relief once his prosthetic was off.

Astrid was still awake, though soon after he relayed the information she begged off to sleep. Hiccup figured he should try too, his mind never calmer than after he'd sated the need for blood. His mother disapproved of Hiccup dating, not because she didn't want him to meet somebody, but because it was somebody who could find him out. She knew she couldn't stop Hiccup killing short of turning him in, and her ultimate goal was keeping Hiccup out of prison. Which Hiccup obviously appreciated.

But when Astrid texted him again, he couldn't help texting back.

Hiccup was... complicated, Astrid realised quite quickly. He wasn't chatty, but equally he wasn't disinterested in what she had to say. She felt like he was listening the whole time, and while he didn't make eye contact much he still focused on her face. Random words would bring a cloud down in his eyes, dark with thought before he shook it off. Over text, he was fine, but by Hiccup's own admission the majority of real life conversation he had was with the mother he cared for.

He was weird about physical contact too - not sex. They were nowhere near that yet, especially not with how much work it was already taking to draw him out of his shell. But if Astrid initiated a hug, he'd tense before he responded. He still flushed when she kissed his cheek, let alone the few times they shared on-the-mouth kisses. Astrid had strong suspicions he was a virgin, but didn't feel it was the time to ask yet. She hadn't forgotten though, his hands in the park brushing spots on her head as he described the danger of impacts here and there.

"So, how is your new book coming along? Have the police dragged you in yet?"

"Not yet, but I'm sure when it's published they'll try and convince me to confess to being the Night Fury. Did you see the latest one?"

Hiccup returned a hesitant nod.

"In the paper, yeah. The police have nothing, again, I gather."

"Yep. And since the killer in my books marks his victims too, I'll probably get questioned. It's not my fault the Night Fury ripped me off!"

Hiccup cocked his head, sipping from the mug in his hand.

"Did you start writing before they started killing?"

Astrid opened her mouth to answer, then closed it again to consider dates.

"Nobody is sure when, there's a couple of kills that were close but not identical, but then serials can escalate or adapt their MO sometimes and I am a little too into serial killers, sorry."

He shook his head, gestured.

"Go on, it's fine."

"Really?"

Hiccup bobbed his head, sipping again.

"The first words I heard from you were about somebody being hit in the head with a pipe. I read your book before I agreed to go on a date with you. I know what you're 'in to', as it were. So, as you were."

Astrid spared a moment to marvel at how he was already the most understanding guy she had ever encountered when it came to her writing, especially given the content, and then she was back on the topic of the obsession her mother wished she'd lose.

"Well, there was this one where the victim was basically pulverised, and burned with cigarettes rather than branded, but if that was the Night Fury's first, then maybe they didn't have the thing they use to brand the victims. That was one of the few with any witnesses too."

"Oh?"

"Yeah. This woman said a guy saved her from being raped, and she refused to even describe him to the cops. They threatened to charge her with assisting an offender, but since it wasn't premeditated and she was the victim, they had no real case. So maybe there's somebody out there who knows what the Night Fury looks like."

Hiccup frowned.

"Fan of theirs, are you?"

"I don't know about fan, but when you write murder books and there's an active serial killer basically on your doorstep who has an unpredictable pattern but distinctive signature... wow, I am going to scare you off if I don't shut up."

She really needed to stop spouting about serial killers. Hiccup was going to run away, and he looked so cosy perched on her sofa with a mug in his hand and no shoes on. He had socks on, so the foot of his prosthetic leg was hidden but Astrid knew it was there - he'd shown her. She liked that he'd felt he could.

"Seriously, it's fine. Aren't you scared though?"

"Of the Night Fury?"

"Yeah."

"Nope. I mean, I guess serial killers aren't considered reasonable people, but as far as I know the Night Fury has a type and I don't fit it. What about you?"

He blinked, putting his mug down now it was empty and tapping fingers against his thigh.

"I don't think I know as much about the Night Fury as you, but I don't think I'm the type. I don't go out at night anyway. I don't even go out much in the day."

Astrid grinned.

"Then I'm honoured you made the effort for me."

Hiccup smiled.

"I enjoy your company. Which is a rare thing in itself. Even when you want to talk serial killers."

"I can talk about something else."

"Sure you could, but like I said, I knew what I was in for. And I am genuinely curious about your book."

There he went again, being all sweet and sincere in his quiet, introverted way. Astrid really liked him. Would-jump-if-he-showed-interest liked him. But Hiccup was obviously a slow mover, and Astrid wasn't going to push it. She was capable of patience. It wasn't like he was a Danish pastry...

"Well, if you're sure... I'm kinda stuck on a couple of scenes. Mind soundboarding like in the park?"

She suppressed a pleasant shiver at the thought of his hands, his voice... Hiccup nodded, smiled.

"Sure."

Astrid got them fresh drinks, sat cross legged at the other end of the sofa to him, one of her notebooks in hand. Hiccup pulled his legs up, put a cushion under the knee of his shorter leg, then nodded at her to go.

"How oblivious do you think someone can be about it?"

"What do you mean? About a serial killer?"

"Yeah. Is it possible to like, date someone who's out there doing it and not know?"

Hiccup hummed, tracing a finger around the rim of his cup and staring off to the left. Astrid tried not to get distracted by his hands. He had such big, dextrous hands...

"Well, there's countless cases of serial murderers and rapists who were married with kids, jobs, even pets. As far as I know, pets tend to be early victims of killers. I guess some could have been lying about not knowng, but... I don't know, I think it's possible. It would depend on how they compartmentalised."

"Is that possible? To seperate it that much?"

He'd switched to drumming his fingers against the side of his mug.

"It depends what sets them off, what kind of killer they are. Like, someone who targets sex workers probably doesn't treat their wife spectacularly, but he also has a very specific target for his anger. If somebody is killing... their mother over and over, but their mother is dead, then they're unlikely to show triggers in front of someone around their own age."

Astrid listened avidly, jotting in her notepad a little before flipping back to a scene she was working on.

"Alright, so dating is a possibility. Oh, hey, question. If you were gonna kill someone, whats the least energy-intensive way you can think of that isn't poison?"

"Ah, the lazy killer. Hmm. Push them off a cliff or tall building? Quick, simple. What about you?"

Humming, Astrid rapped her pencil against her notepad.

"Inject them with air. No mucking about, just a nice straight embolism."

Hiccup actually laughed, putting his cup aside to applaud her sarcastically.

"Oh that's good! Why didn't I think of that?"

"Well clearly, only one of us has the potential to become a murderer."

He didn't answer except to take a swallow of his drink. Astrid hoped she hadn't scared him off.

-HTTYD-

Oh Astrid, your danger-boner is showing

Crofty666 - No. I think the prompt originated on tumblr, got screencapped and dotted around the internet, then ended up on the ATOV Discord server where I encountered it and it sort of grew into a plan for a story.