Hiccup's foot slipped.

This happened frequently; a prosthetic leg was difficult to get used to, after all. He'd spent the months immediately following the battle toting around tears of frustration and pain. Healing had hurt.

So, his foot slipped, metal frictionless against ice.

And he tumbled over the ledge with nary time for a yelp, falling ten feet into steely sea below. Gums lunged forward and clasped on empty air.

Toothless dove after him. The shock of cold penetrated his scales. His keen eyes searched the murky water, finding nothing. He turned his gaze below. Heavy furs and a metal leg would drag Hiccup down, fast.

He propelled himself lower, water darkening as he went. His head darted towards every shadowy shape. He was too deep, he must have missed him.

But then he saw a humanoid figure, and moving closer, it resolved into his boy. His eyes were open, he seemed conscious, but he wasn't moving. Toothless snapped him up in harmless jaws and sped towards the light.

Toothless broke the surface, but Hiccup didn't, still limp in his mouth, Toothless' paws ill-suited to keeping a human's head above water. He released Hiccup, placing his head underneath him and pushing up, so that he slid over Toothless' neck and onto his back in an ungainly heap. For a terrifying moment, he was still.

And then he burst into a fit of coughing and gasping. Frigid air sliced into him, and he shook violently. "Toothless…" he groaned.

Toothless crooned, huge with joy and relief. Feet (or foot, really) found their way into stirrups. Hiccup draped himself across him, icy arms clinging weakly to his neck.

Toothless swam ashore and dumped Hiccup onto the sand. He whined in protest, curling in on himself. Toothless tugged at his vest. Hiccup tried to slap him away, and he tugged harder.

Eventually, Hiccup gave in. He stood, slow, unsteady, and stripped off his sodden layers. His skin was alarmingly pale.

Toothless let warmth spread inside him, turning his body into a furnace. His scales dried like water from a pan over a burner. He swept his shivering boy up with his tail, and he stumbled into his side. He rolled onto the ground, pulling Hiccup down with him. He wrapped him wings around him, forming a dark and warm cocoon.

He felt the small body shift and rumbled comfort, vibrating deep in his chest. Here, alone on this pale beach, he couldn't help but be reminded of choking on ash, injured but only caring for the boy in his embrace. He'd needed him to live.

He drew Hiccup closer. He would live.

Toothless needed him to.