According to Paddy Considine, the terrible condition reflects the situation in which King found himself.
Paddy Considine has revealed the name of his character Viserys I Targaryen's illness in the Game of Thrones universe series House of the Dragon.
Viserys named his daughter Rhaenyra (Millie Alcock) as the heir to the Iron Throne in Episode 1 of the show. However, the character's cronies tried to convince him to appoint Prince Aegon, son of Viserys and Alicenta Hightower (Emily Carey), as his successor. Viserys wanted to secure a better future for his children and Westeros as soon as possible and decide whether to leave Rhaenyra as heir or choose Aegon as his successor.
In many ways, Viserys was in such a hurry to make important decisions for the kingdom because of an illness that is rapidly destroying him from within. Viserys had even lost two fingers because of his condition. In an interview with Entertainment Weekly, Paddy Considine confirmed that Viserys has leprosy. According to the actor, the disease epitomizes the difficult situation the king finds himself in.
Viserys health is declining and his bones are deteriorating at an alarming speed. He's not old, though — he's still a relatively young man. This disease is a metaphor for what it's like to be a king under pressure, feeling exhausted and stressed out all the time.
Fans have long noted Paddy Considine's unparalleled acting, admitting that in just a couple of episodes Viserys has managed to become one of their favorite characters along with Daemon. "I'm looking forward to see how much is too much with his injuries, how long into the series it'll take for him to finally bite the dust and what exactly it'll be that'll do it in the end," as Redditor u/adamnick_ put it.