If there wasn't a war in the step-stones, and he wasn't the main power (followed by the people there) in the second most important house in the kingdom.
Imo it was more sensationalism, which is why I wondered if it is part of the book and played out that way. We should have at least one person in the thread who read that book, so he can tell us ^_^
I read the books, but it was a few years ago. Some characters or plots that the show has made memorable were so minor in the book that I'd completely forgotten they existed.
Vaemond is one of those minor forgettable characters, so I had to check the wiki to remind me about him.
Vaemond Velaryon was a knight from House Velaryon during the reign of King Viserys I Targaryen.[1] He had two sons, Daemion and Daeron Velaryon.[2]
awoiaf.westeros.org
It would indeed be the more interesting development.
That said, since when can a woman inherit the throne in Driftmark (or how it's called) ? (ie have any authority to dictate what happens there; I know she didn't get the seat herself)
It's also quite interesting that no one minds killing the nominally first in line of the second most powerful house in the realm. I doubt many in that place care about the (Strong) boys.
How was it in the books? (assuming it happened there too)
Reminds me somewhat of how no one cared in GoT show Sunspear about their king being assassinated by a Sand and her children.
PS: I liked the actor who played Corlys' brother. Too bad.
The rules of secession was never written in stone, but in general the tradition in most of Westeros is that a daughter may inherit after her youngest brother but before any of her uncles.
Vaemond should not be next in line. Even if Rhaenyra's children were proven to be bastards and not legitimized, Laena and Daemon's daughters are ahead of him to inherit the Driftwood Throne, the Isle of Driftmark, and the castes of Driftmark (a dank old fort where the Velaryons lived since before the Doom) and High Tide (the fancy palace Coryls built for himself).
Vaemond actually is not Coryls's brother in the book. He is only the oldest of his six nephews. It does not seem that they were ever close.
I'm not sure if Coryls even has any brothers in the book. Having nephews implies he has siblings, but maybe they were sisters. Despite the show having his discuss the Westerosi custom of children taking their father's names, it is not actually uncommon for children to take their mother's name if the mother's house was of considerably higher status, such as when a daughter of a highborn lord marries a lowborn but wealthy merchant or if a female heir of great lord with no sons marries a second son of a lesser house. I think it was also stated that if Harrold Hardyng inherits the Vale from his 2nd-cousin-once-removed Sweetrobbin that he would be required to change his surname to Arryn.
I believe the book said that one of the laws passed by Old King Jaehaerys on the advice of Good Queen Alyssane allowed a widow to stay in her husband's house, keeping any titles she had as his consort and being maintained in the lifestyle to which she was accustomed, unless or until she remarried. It also let her be regent for any heirs until they reached the age of 16. (In the book, Rhaenyra's oldest son is only 12 and Laena's twin daughters are only 10 when Coryls gets the fever and Vaemond tries to become his heir. Viserys lives 3 more years after that, so perhaps by the end of the episode they are 15 and 13.)
I'm pretty sure the whole throne room scene was completely made up for the show. The wiki says in that in the book Rhaneyra sent Daemon to seize Vaemond, decapitated him, and fed him to her dragon. Viserys then ordered 5 of his cousins to have their tongues removed for spreading rumors of his grandsons being bastards.
The book gives no hint of how ill and decrepit Viserys was. He does not have leprosy or a missing eye, but he is obese and drinks too much. He is barely 52 years old when he dies.
I like the tension between the Targaryens and the John Strongs

I hope the Velaryon leader is actually alive, and suppose he would be against what his wife did (since ultimately he cares more about the throne; he already experienced being leader of the Velaryons).
Besides, he should take revenge for his brother.
He doesn't have much reason to oppose what his wife did. He was always insistent that names mattered more than blood. He was the one who wanted Lucerys to be his heir, rather than considering Laena's daughters or Rhaenys wanted much less letting it fall to Vaemond. It seems to be implied that he and Vaemond never got along.