Phoebe Campbell as Rhaena Targaryen in the Season 3 premiere of House of the Dragon. —Theo Whiteman—HBOWarning: This post contains spoilers for the Season 3 premiere of House of the Dragon.After spending the majority of Season 2 of House of the Dragon caring for the younger sons of Rhaenyra (Emma D'Arcy) and lamenting her status as a dragonless Targaryen, Rhaena (Phoebe Campbell) spotted an opportunity to change her fate by claiming the wild dragon Sheepstealer—and in the Season 3 premiere, she capitalized on it.When we last saw Rhaena in Season 2, she was scurrying around the valleys of the Vale in hopes of finding Sheepstealer and making good on what seemed like her last plausible shot at securing her own dragon. In Sunday's premiere, we saw her mount Sheepstealer for the first time and prove herself to be a worthy enough rider for him to hunt and barbecue a meal for her. This moment seemed to confirm fan speculation that Rhaena is taking over the role of Nettles—an important character from George R. R. Martin's Fire & Blood, the A Song of Ice and Fire companion book on which House of the Dragon is based—in the show's version of the Dance of the Dragons.What happened with Rhaena in the Season 3 premiere?Dragons fly into the fray at the Battle of the Gullet. —HBOLike Nettles does in the book, Rhaena then flew Sheepstealer into combat at the Battle of the Gullet, where she quickly learned dragons are not always amenable to obeying their riders’ commands. Although Rhaena entered the battle to aid her sister Baela (Bethany Antonia) and step-brother Jace (Harry Collett) in the fight against the Triarchy’s forces, Sheepstealer took it upon himself to begin attacking their dragons, Moondancer and Vermax.Once Jace realized Rhaena was Sheepstealer’s rider and commanded Vermax to pull back to avoid killing Rhaena, Vermax was forced to dive within range of the enemy ships and was pierced with a massive grappling hook that dragged him under the water, drowning him. Then, when Jace unhooked himself from his harness and swam to the surface, he was quickly shot and killed by enemy crossbowmen. Not a great first dragon outing for Rhaena!How is Rhaena's story different in the book?Rhaena (Phoebe Campbell) searches for Sheepstealer in House of the Dragon. —Theo Whiteman—HBOLike in the show, Rhaena misses out on a few different chances to bond with a dragon in Fire & Blood. Although she is given a dragon egg at birth, in the book, the hatchling is unhealthy and dies hours after being born (in House of the Dragon, the egg simply never hatches). Aemond (Ewan Mitchell) then covertly claims her late mother's former dragon, Vhagar, before Rhaena can ever give it a go. The show also mentions that Rhaena once tried to claim Seasmoke, the former dragon of her Uncle Laenor (John Macmillan), Seasmoke, but almost died in the process.However, Rhaena does ultimately come into possession of a dragon in Fire & Blood when one of the eggs she takes with her to the Vale hatches. This dragon is named Morning, but isn't big enough during the Dance to participate in any battles or really make a difference.Who is Nettles?In Fire & Blood, Nettles is a lowborn teenager who is described as "foul-mouthed, filthy, and fearless," and is considered a dragonseed. However, unlike Addam, Hugh, and Ulf, it's unclear whether she actually has any true Valyrian dragonlord heritage.Instead of claiming Sheepstealer by traditional means, she instead befriends the wild dragon by bringing him a freshly slaughtered sheep to eat every day until he gets comfortable around her. She's also the only female dragonseed and, in the book, the only canonically Black character. How will this affect the future of House of the Dragon?Lohar (Abigail Thorn) prepares to fire a grapnel at Vermax in the Season 3 premiere of House of the Dragon. —Ollie Upton—HBOSince it seems like Nettles' duties will now pass to Rhaena, we won't get into the specifics of everything the fan-favorite character does to assist Team Black throughout the Dance of the Dragons. But the switch-up implies there's one important Nettles storyline that likely won't play out with Rhaena in the same way it did in the book.In Fire & Blood, Daemon (played by Matt Smith in the show) and Nettles grow close as the Dance progresses and, by some accounts, even become lovers. When Mysaria (Sonoya Mizuno) feeds this rumor to Rhaenyra, it enrages her and prompts her to try to have Nettles beheaded. Nettles then flees and is never seen at any Westerosi court or castle again.Since Rhaena is Daemon's daughter and—as we learned from Daemon's Harrenhal-induced dream about his mom—even the Targaryens aren't keen on crossing that parent-child relationship line, it seems safe to assume nothing of the sort will happen between the two. But Rhaena replacing Nettles is still likely to shake things up in other ways and have some significant implications down the road.