Rhaenyra quickly took out many of the illegitimate Targaryens in the search for a dragonrider in House of the Dragon Season 2, Episode 7. One of those Targaryens was Silver Denys.
Don’t worry if you missed it. The only reason a lot of people know that Silver Denys was in the story is due to social media. The character wasn’t named in the series, and the storyline didn’t follow that of the book.
Silver Denys was one of those who tried to claim Vermithor at Dragonstone. His storyline is a little bigger in the book, and it’s not him trying to claim Vermithor, but another dragon.
Silver Denys goes after Sheepstealer in Fire & Blood
Rhaenyra doesn’t call everyone to Dragonstone in Fire & Blood. She doesn’t have them all attempt to claim Vermithor at the same time. Instead, she tells them she wants those with Targaryen blood to attempt to claim dragons.
There are three wild dragons in Westeros: Grey Ghost, Sheepstealer, and Cannibal. It’s the latter two who are involved in Silver Denys’s storyline.
Denys goes after Sheepstealer, the wild dragon who is around the Vale. We have presumably met this dragon in House of the Dragon. This is the one Rhaena comes across at the end of the second season, although that doesn’t happen in the books.
Sheepstealer rips Denys’s arm off. While his sons attempt to staunch the wound, Cannibal swoops in and kills them all. It’s the end of that line, which may or may not come from Maegor the Cruel.
The change overall affects nothing in the books. It’s not like this change affected who ends up with dragons. The change of Rhaena going after Sheepstealer is the thing that changes that, and not in a good way.