A/n: This is an idea sent via pm by TNTkinetic and written by me at that time in the morning where you don't remember any of it. Welp, have it anyway.
Of all the things Hiccup had expected to be faced with that day, he could honestly say that this wasn't one of them.
"A shark?" he said, borderline incredulous, "You face fire breathing, acid spitting, island eating dragons every day, but a shark causes you problems?"
"Yes." came the typically blunt reply.
"Alvin the Treacherous? Trouble with a -"
"I already said yes!" Alvin snapped. "I wouldn't have come to you unless I was desperate, and you know it!"
Hiccup did know it. Alvin hardly ever visited Berk, and his arrival was never to announce a new dragon species or have a nice chat. "Okay," he said, calming down slightly, "When you say shark, you mean..."
"A massive shark!" Alvin growled. "It's killed half my men, and I'm not letting it kill any more."
"Why don't you just... kill it?"
"I can't. When I say massive, I mean bigger than that bewilderbeast everyone's been harping on about."
Hiccup seriously doubted that, but the comparison did put things into perspective. "Right. Me and Toothless will check it out; give me the general location and we'll find it."
The shark wasn't that hard to find. It was just off Outcast Island's south coast, as promised, and was as big as it had been described.
"Not as big as the bewilderbeast..." Hiccup insisted quietly, pressing himself as close as he could to Toothless to allow for maximum stealth.
The water surrounding the shark was quiet, too quiet, and Hiccup had a pretty good idea why.
'Okay. Let's just sit tight for a while, see if we can work out any weak - oh,' he stopped, squinting down. 'Never mind, there's a dragon down there. Off we go, then.'
Toothless nodded, and the two dived down to rescue whatever unfortunate dragon was about to cross paths with the deadly shark. It was a seashocker, who already looked worse for wear. A quick plasma blast to the shark's side distracted it enough to let the tidal class dragon make its escape, and the battle was officially rushed into.
The shark was at a disadvantage from the start, having no power of flight and already taken a hit to the side. It did have exceptional strength and speed, as well as stamina, so it managed to endure the first hit enough to dodge the barrage that followed. After a minute of firing and missing, it became apparent that long range attacks just weren't quite going to cut it.
'Switch to automatic,' Hiccup ordered. Toothless let out a concerned whine as he complied, knowing Hiccup well enough to see where the action was going, and fearing the worst that could happen from the new plan. 'It'll be fine,' Hiccup assured before he jumped, pulling out his wings and sword as he flew overhead.
The shark had its first encounter with zippleback gas, soon followed by fire after a quick spark. Once the flame cleared, Hiccup took advantage of the shark's distraction to land on it, standing on its back and jamming the flaming sword into it.
"Take that!" Hiccup yelled, smiling in satisfaction as the shark started to sink. "Little help?" he called to Toothless, who responded with a few quick plasma blasts to finish it off before swooping in to rescue Hiccup.
"That wasn't so hard." Hiccup noted. Though, as a pair who'd managed to take down two alpha dragons by now, it was difficult to find something they classed as 'hard'. "Time to tell Alvin to go home."