Ruth is a white dragon, unique among his species, whose Rider is Lord Jaxom of Ruatha Hold. He is capable of travelling to any When in time, and fire lizard's obey him. Due to his small size he is often the victim of ridicule.
Ruth is the only white dragon mentioned anywhere in the Pern novels. He is not an albino, as his hide contains very faint patches of all the normal dragon colors, visible on close examination when Ruth is very clean.
When Jaxom was young, Lord Warder Lytol took him to a Benden Hatching. Before the Hatching itself had begun, Jaxom and Felessan had gone down to take a peek at Ramoth's Clutch, and there Jaxom noticed a grey egg smaller than all the rest. Jaxom felt sorry for the little egg and gave it a pat.
At the Hatching, the little egg did not hatch at first, and Jaxom, seeing that it was rocking, leapt down to the sands to help the dragonet break through the unusually tough shell. Using his belt knife to cut through the membrane, a white dragon tumbled out, less than half the size of its clutch-mates, and Impressed Jaxom. The dragon's name was Ruth.
At the time of Ruth's hatching there was disagreement over what would happen to the newly Impressed pair. It was a commonly held belief among the Pernese that, whatever plans have been made for the future, they must be cancelled in favour of the Weyr's. However, the lack of a Lord Holder had also previously nearly caused all-out war, which only ended with Jaxom's birth and his father Fax's death. The Lords Raid of Benden and Sifer of Bitra contended that Jaxom should yield lordship of Ruatha, while Masterharper Robinton and Lord Warder Lytol maintained that Jaxom should remain at Ruatha. Lord Lytol, defending Jaxom's actions and certain that Ruth's days were numbered, stated that Jaxom should stay where his obligations would give meaning to his life after Ruth died. The Masterharper and Lord Lytol prevailed and both Ruth and Jaxom were removed to Ruatha where they prospered.
Ruth stayed in his own personal weyr at Ruatha Hold, and despite most expectaions, grew into adult size... at least for him. He was still very small compared to his clutchmates and other dragons though, and it was not certain that he would even be able to fly. At his first flight, Weyrleader F'lar took the unusual step of examining Ruth's wings for size and strength, determining that Ruth did have a proper wing-to-body size ratio. Ruth surprised all in attendance with a very quick vertical lift-off and proved to be an excellent flyer, having great speed. Ruth's smaller size, rather than being a hinderance, allowed him to be nimble and agile in the air, allowing what is usually described as being able to "turn on his own tail", what the ancient humans of Earth called "turning on a dime".
Jaxom and Ruth were attending a training session at a weyr when a mating flight also happened to take place. Despite being sexually mature, Ruth had absolutely no interest in competing with other males, while Jaxom himself was affected. Indeed, the very concept of a having a mating urge appears to puzzle Ruth. He is sometimes affectionately teased about it by his rider and others, asking him what he thinks about chasing females, what he would consider to be only a race; his general reaction can be summed up as "... but why would I want to?" Jaxom would come to sum up Ruth's lack of a mating urge by explaining that Ruth is a sport. This likely is meant in a biological sense, when an organism or part that shows an unusual or singular deviation from the normal or parent type; or in other words, a mutation.
Ruth is not only different physically, but mentally as well. He is an unusually intelligent member of a fully sentient species, having greater memory and being able to grasp concepts much more easily than other dragons. F'lessan's bronze Golanth once noted that Ruth was one of the dragons who would listen in on Jaxom's lessons with Aivas. Ruth's opinion appears to be well regarded by other dragons. His intelligence also allows him to easily orient himself during time travel.
Just as Jaxom had unique circumstances that affected his life, Ruth's birth, small size, having a Lord Holder-in-training for a Rider affected him. Ruth grew up at Ruatha Hold, and not at a weyr as all other dragons had for centuries. As a result, Ruth became more independant and is occasionally more impulsive that the usual dragon, having not been raised in a weyr-established lfestyle. Lytol has commented thought that Jaxom's cautiousness gives balance to the pair.
Because of his smaller size, fire-lizards are often fascinated with Ruth; Ruth has explained that they like him because they do not have to be so far away in order to see him in his entirety. He will often times be swarmed by them when he goes for a bath, quite willing to help out. As a result, when Ruth tells fire-lizards to do something, they will do so immediately, whether they are wild or not.
As with all dragons, Ruth is well regarded by other dragons, but greens especially respect him, even when they won't listen to their own riders. He is on good terms with his parents, and has mentioned that his mother likes to boss him around.
It seems likely that white coloration in dragons is normally a lethal mutation, as it is tradition to not assist dragonets who can't hatch on their own. It appears that a white dragonet is unable to break out of their own egg, perhaps due to possibly inadequate strength of the dragonet or the unusually tough shell of a white's egg such as Ruth's had, or a combination of both. Although his parents are the largest queen, Ramoth, and largest bronze, Mnementh, in the history of Pern, Ruth is smaller than even a normal green dragon in his time; he is only slightly larger than the largest dragons of the first generation. While his exact length is never specifically mentioned in the books, it does state that he stands higher than a runnerbeast (horse) at the shoulder, extrapolations suggest that he might be eighteen feet long. He is male or neuter (undetermined), and assumed sterile, with no urge to mate.