Caraxes
A lean, red, ill-tempered dragon, well matched to the most dangerous man of his age.
The beast itself
Caraxes was wrong-looking, and everybody said so. He was red ÔÇö a dark, wet, arterial red that people compared to meat rather than to fire ÔÇö and he was built along entirely different lines from the barrel-chested beasts around him: enormously long in the neck, narrow through the body, all sinew and no spare flesh, so that in flight he looked less like a dragon than like something eel-shaped that had learned the trick. The Blood Wyrm was not a compliment when the name was coined. It stuck because it fitted.
The noise he made is the thing the chronicles keep returning to, and no two of them describe it the same way: a scream, a shriek, a whistle, a sound like a knife on a whetstone drawn out far too long. Horses would not stand near him. Neither would most men. He was quick-tempered, restless, forever shifting his weight and turning his head, and he had the settled dislike of human beings that dragons usually only develop in the wild. He would snap at handlers who had fed him for years. There is no account anywhere of Caraxes being described as calm.
His first rider: Aemon Targaryen
Long before the war, Caraxes belonged to the Old King's eldest son. Prince Aemon was heir to the Iron Throne, a serious and well-thought-of man, and he flew the Blood Wyrm on the sort of duties an heir gets: showing the flag over the Stepstones, standing over royal progresses, putting down pirates who had grown too confident. It was a competent, unremarkable partnership of the kind that a long peace produces, and it is chiefly worth noting because of what came after ÔÇö the dragon spent twenty years being ridden correctly by a careful man, and then spent the rest of his life being ridden by someone entirely different.
His second rider: Daemon Targaryen
Daemon claimed him at sixteen, which was reckless even by the standards of a family that made recklessness a policy, and the fit was immediate and total. A restless, thin-skinned, violent dragon and a restless, thin-skinned, violent prince spent the next four decades in each other's company, and neither of them noticeably improved the other.
What they did together was mostly war, and mostly war chosen rather than inherited. Daemon took Caraxes to the Stepstones and spent years there carving out a kingdom out of rock and pirates, and the two of them came home from it as the only genuinely blooded dragon-and-rider pair in the world ÔÇö everyone else's beast had spent the peace being led out of a stall to impress lords. That experience decided more than one engagement later, when Caraxes proved to know things about fighting in the air that dragons twice his weight had never had cause to learn.
Seen from outside, the bond frightened people in a way the other pairings did not. Daemon flew low, deliberately, over places he wanted to make a point to. He put Caraxes down in courtyards without asking. When the two of them took Harrenhal early in the Dance they did it with no army at all, a rider and a dragon and a very short conversation, and the castle changed hands before the news of it did.
The dragon in the songs
Caraxes has fared better in the singers' hands than in the maesters'. To the Citadel he is a case study in what happens when a dangerous animal is matched with a dangerous man; to the harpers of the Riverlands he became something closer to a devil that could be summoned by insulting the wrong prince. The Stepstones years in particular grew in the telling until Daemon was fighting pirate kings in single combat with the Blood Wyrm circling overhead like a witness. Some of that is true. The proportion is disputed and always will be.