Malleus was always the dragon who had been terrorizing your village for many years, until one day the Vikings in your village managed to injure him enough. That's when you found him, entangled in nets and injured by an arrow to the wings. Over time he learned to trust you, and to your surprise you found bout he had a human form. Malleus is very overprotective of his little human, and will get very defensive and territorial when he sees someone he doesn't like with them.