Spoiler Alert: This article contains spoilers for Season 1 of House of the Dragon.
Rhaenyra would be the first Targaryen queen, but Viserys' brother Daemon wants the throne — and Alicent Hightower has already married Viserys and given him a son. (It would be in line with tradition for Hightower's son to take the throne).
There are many possible heirs vying for the throne, and that's why the king has to die for the story to move forward effectively. The question becomes not if the king will die, but when and how.
What is King Viserys dying from in 'House of the Dragon'?
King Viserys had a relatively easy time ruling his kingdom. Since his father Jaehaerys I passed the crown to Viserys, Westeros has been peaceful. However, Viserys isn't a successful king by any standards. He's selfish, passive, and impulsive. He is willing to let his wife die for a son, but his decision to marry Alicent over the young Lady Laena Velaryon shows he's not willing to sacrifice his own comfort for his kingdom.
If you were hoping Viserys would meet a fate as terrible as the one he put his wife through, you might be disappointed. Viserys is a character who represents passivity. He is indecisive and lazy — the show even manifests a physical representation of these characteristics. He's diseased by the many cuts he receives while sitting on the Iron Throne, literally rotting away on the seat of power.
In episode five, he coughs up blood and struggles to get through speeches without intermittently coughing. While on EW's West of Westeros Podcast, Paddy Considine, the actor who portrays the king, revealed that the character is dying from some form of leprosy.
The slight cuts he has received refuse to heal and have only worsened in intensity. His inevitable demise (which may just happen before the season ends) is symbolic of the king's weakness, as well as the eventual downfall of the Targaryens.
One day, Viserys will simply die in his sleep, according to the Fire & Blood books the show is based on. But the news doesn't get out right away. Alicent orders the king's death to remain a secret while she plots to have Aegon take the throne against the king's wishes. As if becoming queen regent is her fair payment for all that time spent married to a decaying elderly husband.
Does Daemon Targaryen eventually become king?
When Daemon and Rhaenyra on Dragonstone hear the news of Viserys' death, Rhaenyra rejects her half-brother Aegon's claim, and Daemon supports her.
While Daemon postured at being king, he loves and supports Rhaenyra enough to put that aside and help her take back the kingdom. No, Daemon does not become king, but he does become Rhaenyra's husband, and together they'll try to reclaim the throne.
Despite not ascending to the Iron Throne, creator George R.R. Martin named Daemon as his favorite character in the series.
"I’m notorious for my love of grey characters and one of the greyest characters in the entire history of Westeros is Daemon Targaryen, the Rogue Prince," he shared in an interview. "He's a very colorful and unpredictable character and he has to rank up there as one of my favorites."
Watch House of the Dragon Sundays at 9 p.m. EST on HBO.