Rhaenyra Targaryen had a total of six children, not just three. She had three sons with Laenor Velaryon (Jacaerys, Lucerys, and Joffrey), and three more children with Daemon Targaryen (Aegon, Viserys, and a stillborn daughter, Visenya). Her first three sons were widely rumored to be fathered by Harwin Strong.
In the recent season finale of House of the Dragon, Rhaenyra was forced to deliver her stillborn child after first learning of the death of her father, King Viserys.
It was rumored that those sons of Rhaenyra's were actually fathered by her lover, Harwin Strong, called "Breakbones". All three were born with brown hair, brown eyes, and features considered "common" such as a pug nose.
After Viserys declared Rhaenyra as his rightful heir, the furious Daemon left for Dragonstone and took Mysaria with him. They remained there for six months, during which time Mysaria became pregnant; when Daemon learned of her pregnancy, he gave her a dragon egg, and by that infuriated Viserys.
Game of Thrones' Drogon chose not to kill Jon Snow because of his Targaryen blood, his love for Daenerys, and Drogon's possible understanding that while Jon committed the act, he wasn't the reason for Daenerys' death at the end of Game of Thrones'.
Baela and Rhaena Targaryen
Baela and Rhaena are the two daughters of Daemon and his second wife, Laena Velaryon (Daemon killed his first wife Lady Rhea Royce, and made it look like a hunting accident). Laena died while she was pregnant with her third child; she demanded her dragon to kill her during a difficult labour.
Visenya Targaryen (figlia di Rhaenyra e Daemon) Visenya, like other Targaryen babies who were stillborn, are described with dragon characteristics, such as scales, wings and a tail, and although some think it is due to incest, it is actually because the Targaryens really are of the blood of the dragon, it is said that ...
At the opening feast, the queen wore a green grown, while Princess Rhaenyra wore typical Targaryen colours of red and black. According to Septon Eustace, prior to Rhaenyra turning sixteen, she had lost her virginity to her uncle, Daemon Targaryen after he seduced her.
Helaena and Aegon had three children: the twins Jaehaerys and Jaehaera, and Maelor. Like her siblings, Helaena was a dragonrider, who rode the dragon Dreamfyre.
Alicent dies three years after Rhaenyra in "Fire and Blood."
Rhaenyra struggled to keep the smallfolk happy because she raised taxes to afford the conflict. Three years after Rhaenyra's death, Alicent is placed under house arrest because she fails to persuade her granddaughter to kill Rhaenyra's last surviving son.
Ever since she was cursed by Mirri Maz Duur back in the first season of the show, Daenerys believed that she would never be able to have children.
The warlord, desperate for having a healthy heir, would routinely rape the women and make sure they would deliver healthy babies for him. In most cases those attempts were futile until Angharad became pregnant with his child. Immortan also impregnated the Dag, however the fate of that pregnancy remains unsolved.
Although the specifics are unconfirmed in the novel, Vhagar, as the oldest she-dragon, has laid eggs before and these eggs have hatched. That means a lot of the other dragons such as Aegon II's Sunfyre and Rhaenys' Meleys who were both attacked by Vhagar in 'House of the Dragon', could be Vhagar's children.
In the A Song of Ice and Fire novels, the Targaryens continued to incestuously marry brother to sister "to keep the bloodlines pure" as had their ancestors in the Valyrian Freehold. For a time, at least, they also continued to practice polygamous marriages.
Syrax. Syrax is a yellow-scaled dragon who has only ever had Rhaenyra as a rider. She was claimed when the princess was only seven and was named Syrax after the Valyrian goddess. Unlike most dragons which are born male, Syrax is one of the few living she-dragons.
Ser Criston Cole: According to Martin's The World of Ice and Fire, Ser Criston was born in 81 AC, making him 16 years Rhaenyra's senior. But Dragon's Ser Criston is likely much younger: Fabien Frankel, who portrays the knight onscreen, was only 8 years older than Alcock's young Rhaenyra during season 1. (He's 30 now.)
The Targaryens after the Dance followed male inheritance or else one of Aegon III's daughters would've been Queen. Which means that Daemon was ahead of Rhaenyra in succession, making Aegon III king because of Daemon.
Whether or not HBO knew Arya's sex scene would cause a stir online remains to be seen, but the network did get ahead of any potential controversy by confirming Arya is 18 years old in a social media post published hours before the episode aired.
In desperation, Daenerys asks Mirri Maz Duur to heal Drogo with blood magic. Despite being saved by Daenerys from being raped by the tribe's warriors, however, the priestess betrays her and the magic ritual results in Daenerys's unborn child being stillborn and leaves Drogo in a catatonic state.
Vhagar was twice the size of Drogon and older/more experienced in battle. Wouldn't even be a close fight. Vhagar has upper hand that's for sure !!!
During the Dance of the Dragons, Hugh Hammer, Ulf the White, Addam of Hull, and Nettles were all found to be capable dragonriders. They were suspected to be Targaryen bastards, but never confirmed in the text. In particular, Nettles is sometimes pointed to as likely not a Targaryen.
Laena suffers from complications during her third pregnancy. After Daemon is informed that it would perhaps be possible to save the baby through the use of a caesarean section, Laena resolves to die a dragonrider's death, walking to Vhagar and commanding the dragon to incinerate her.
Rhaena Targaryen, Daemon's daughter, wasn't an ancestor of Margaery Tyrell. Rhaena married into the Hightower family, but the Hightower line didn't continue through her since she was married to a third son. Margaery's mother was a Hightower from a different branch, descending from Otto Hightower's brother.
Inbreeding: The Targaryens practiced sibling and cousin intermarriage to "keep the blood of the dragon pure" and preserve their unique Valyrian traits and connection to dragons.