Spike is a male red Deadly Nadder, and is Asta's dragon, and best friend. He used to live in the wild, but now resides in the Mongrel Village on Mongry Island.
Spike is a very noble, and loyal dragon, but before he met Asta, he was wild, and protected his territory fiercely, even chasing out other Nadders. He was a greedy dragon, and often raided other dragons'nests for their food.
However, his selfish, and rogue-like nature changed when he saw Asta wash up on shore, unconscious. He had considered leaving her behind, but not before he saw a Leviathorgan reaching out of the water to eat the young viking. Suddenly protective of the small, fragile girl, Spike leapt out of the forest, and drove off the water dragon with his tail spines. He left when Asta began to wake up, leaving only his footprints behind. As Asta stumbled through the forest, looking for civilization, Spike stalked her, watching her from above in case any other wild dragons attacked, and only showed himself to her when a band of Smothering Smokebreaths chased her to the edge of a cliff. He leaped to her defense, driving away the smaller dragons. From then on, he stuck close to Asta's side, hunting for her, and making sure she had a fire going at night. He became so attached to her that eventually, when Sindbad and Furnace snatched her to take her away from the wild dragon, and to the Mongrel Village, Spike chased after the Typhoomerang, and his rider, convinced that they wanted to hurt Asta.
Eventually, Spike was given his name, and was trained by Asta, allowing her to ride him. Though he is still greedy, and loves to eat, he will drop everything he's doing to protect Asta, and her friends, including other dragons. Over time, he eventually began to show signs of extreme intelligence. While most dragons only respond to simple commands such as "Fire!" or "Attack!", Spike is able to understand exactly what Asta is saying, responding to her with huffs of agreement, or grunts of dislike, suggesting that the Nadder's intelligence is almost equal to that of a Night Fury.
- There is a distinct possibility that Spike is related to Stormfly is some sort of way.
- His intelligence makes people wonder if he came into contact with Night Furies in a non-aggressive way, resulting in his Night Fury-like behavior. This also suggests that there could very well be other Night Furies around Mongry.
- Despite his vicious behavior, Spike has actually never killed a viking or a dragon, probably because he knew what would happen to him if he ever did. It may also be a result of Asta's pacifistic behavior.