We orcs won’t dignify the tweets of a high-profile ASOIAF person claiming that there were no black Valyrians. We orcs have read the books, and don’t know why there couldn’t be black Valyrians.
There are people in the story who are Valyrian and Rhoynar, and Valyrian and First Men https://twitter.com/houseofdragon/status/1389959318439530499

The Velaryons were from Valyria, just like the Targaryens, but only the Targaryens are described as being obsessive with their bloodline. The Velaryons are a sea-faring people, so it’s not unreasonable to assume their family tree has more opportunities for breadth, instead of -

- the shrubbery of the Targaryen line. Targaryen genes appear to be recessive, which is why the Jonnazgul does not have Rhaegar’s hair and eyes. But if he and Daenerys had a child, their off-spring would likely look very Targaryen. Same with the Velaryons, even recessive Val-

- traits would re-emerge since they often had family members mating with the Valyrian-focused Targaryens. So this casting of Corlys does not break world building, instead it gives the show a more interesting look at the Velaryons.

We orcs miss Game of Thrones, and look forward -

- to House of the Dragon, even if it won’t have the same House Stark focus. We orcs can be patient for Cregan Stark, mighty orc lord, to appear in the story when they eventually get to the Dance of the Dragons storyline proper.

Look, we orcs aren’t experts on genetics, we’re created from tortured elves and other sorcerous means. But we have long views, and think that anyone making claims about impossibility ancestries underestimate the human ability to hook up with one another, and appreciate the -

- beauty of someone who doesn’t look like them.

Perhaps one should imagine the perspectives of Corlys’s parents and grandparents, rather than trying to force one’s own perspective on them.

There can’t be black Valyrians? In House o/t Dragon, the Velaryons respectfully disagree.