Nettles

Nettles is an unseen character in Game of Thrones. She is long dead by the time of the series. She was a dragon-rider for Rhaenyra Targaryen's faction during the Dance of the Dragons.

Biography
Nettles was a bastard scion of House Targaryen - known as one of the "dragonseeds".

Originally she lived in obscurity on the ancestral Targaryen holding, Dragonstone island. Her exact parentage is unknown but she didn't resemble her Targaryen ancestors - instead she was notably dark-skinned (like a Summer Islander).

As the great Targaryen civil war known as the Dance of the Dragons progressed, Rhaenyra Targaryen's faction - which was based on Dragonstone - realized that they had more living dragons than dragon-riders, with six riderless beasts nesting on the island. It is believed that only those of Targaryen blood can successfully bond with and ride a dragon, so Rhaenyra proclaimed rewards for any commoners on Dragonstone who could successfully bond with one of the unclaimed dragons - specifically Targaryen bastards and descendants of Targaryen bastards who had been fathered over the years on commoners of the island by young Targaryen princes.

Nettles was one of only four of the so-called dragonseeds to successfully bond with a dragon, Sheepstealer. She cleverly managed to gain his trust by bringing him gifts of freshly killed sheep until he gradually became accustomed to her presence.

Nettles rode her dragon throughout the rest of the war. After the capture of King's Landing, she accompanied Rhaenyra's husband (and uncle) Daemon Targaryen with his dragon Caraxes, as they hunted through the Riverlands for Prince Aemond Targaryen on the great dragon Vhagar.

Eventually, however, after two of the other dragonseeds betrayed Rhaenyra at Tumbleton, she grew paranoid and began to distrust all of the bastard dragonriders, and sent a letter calling for the young girl's head. Particularly, it was said that Daemon himself had taken Nettles as a lover. Daemon was disgusted when he heard of the order: Nettles managed to depart in safety on her dragon, while Daemon issued a challenge to Aemond to come and face him alone. Daemon and Aemond both later arrived at Harrenhal with their dragons, and in the subsequent Battle Above the Gods Eye both men and both dragons perished.

Nettles and her dragon, however, were never seen again.

In the books
In the prequel novellas, nothing is stated about Nettles's past or family on Dragonstone island prior to becoming a dragon-rider.

Nettles is consistently described as a "small, brown girl". Apparently she was notably dark-skinned: the "Histories & Lore" featurettes similarly depict her as dark-skinned with black/African features. It's possible that she was a Targaryen bastard (or descendant of a bastard) fathered on a woman from the Summer Islands, and happened to take after her non-Targaryen ancestors in appearance (similarly, one of Oberyn Martell's daughters, Sarella Sand, was fathered on a woman from the Summer Isles, but she just happens to take after her mother in appearance). This would make Nettles the only non-white dragon-rider in the history of Westeros (though not the only female dragon-rider: several women in Rhaenyra's faction including Rhaenyra herself were dragon-riders).

At the time she claimed her dragon, Nettles is described as 16 years old and skinny. In dress and personality, she is described as being filthy and foul-mouthed.