Following Princess Aerea Targaryen's taking of Balerion and her death after she returned with the dragon to Westeros, King Jaehaerys I Targaryen founded the Dragonkeepers in 56 AC to prevent another such theft.
In 60 AC, as Princess Daenerys Targaryen was stricken by the Shivers, King Jaehaerys ordered a raven sent to the Dragonkeepers on Dragonstone, ordering them to bring a hatchling to King's Landing at once. After Daenerys died several hours later, Jaehaerys flew to Dragonstone upon Vermithor to inform them that it was no longer necessary.
According to the accounts of the Dragonkeepers, when Princess Alyssa Targaryen came to claim a dragon in the Dragonpit in 75 AC, they had to convince her not to claim Balerion, telling the princess the dragon was "old and slow" and suggesting she would rather have a swifter mount. In the end they succeeded, as Alyssa claimed the dragon Meleys.
Once, when Princess Viserra Targaryen brought six boys into the Dragonpit, promising her maidenhead to whoever would put his head in a dragon's mouth, the Dragonkeepers arrived in time to put an end to it.
During the Dance of the Dragons, less than fifty Dragonkeepers stood guard when the Storming of the Dragonpit began. The greatly-outnumbered Dragonkeepers fought the Shepherd-led mob but were slaughtered when the rabblew broke through. The dragons Tyraxes, Shrykos, Morghul, and Dreamfyre died fighting the mob, and the dome of the Dragonpit collapsed.
A Game of Thrones
Lord Eddard Stark sees empty suits of armor in a deserted corridor of the Red Keep. The armor is of black steel with dragon scales on the helms' crests, so they might have been armor of the Dragonkeepers or other House Targaryen guards.
A Storm of Swords
- Fire & Blood, Jaehaerys and Alysanne - Their Trumphs and Tragedies.
- Fire & Blood, The Long Reign - Jaehaerys and Alysanne: Policy, Progeny, and Pain.
- Fire & Blood, The Dying of the Dragons - Rhaenyra Overthrown.
- Fire & Blood, Under the Regents - The Voyage of Alyn Oakenfist.
- A Game of Thrones, Chapter 20, Eddard IV.
- A Storm of Swords, Chapter 61, Sansa V.