The 49-year-old actor played the virtuous ruler in the new HBO series, based on Martin's fantasy novel Fire & Blood, who was killed off in episode eight of the GoT prequel.
Considine told GQ magazine: “I got a text message that simply said: ‘Your Viserys is better than my Viserys’. It was from George RR Martin. And I thought: that’ll do it. Thanks for trusting me.”
The star of Dead Man's Shoes and This Is England revealed he had a felt a duty to the incorruptible king, and was undeterred when some people on the show were not sure about how he was playing the character.
He said: “I felt like my job was to serve Viserys, and I took it seriously. But for a while, people were unsure.”
And Considine defended the character, who some viewers considered to be weak.
The Peaky Blinders star said: “There’s this perception that he’s weak, which I think is absolutely nonsense. He’s just too compassionate for the job. I think the sense of duty is what got to him.
“He was the only person in this kingdom who had any f***ing morals whatsoever. He holds everything together as long as he absolutely can. I thought he was a joy to play. He believed in duty above everything. I don’t know if people fully understood that correctly.”
Considine added: “What I found really interesting about him was that he wasn't corrupted by power. He just wanted peace. He wanted people to be happy at the end of the day, but that makes him weak.
"So what would have made him more relatable, if he was a dictator? If he was a tyrant? Would that be more satisfying? It's not who he is.”
Viserys's health took a gradual decline from the first episode of House Of The Dragon, when he cut his hand while touching the famous Iron Throne. The poisoned wound led to his fingers rotting off, and the infection eventually killed him.
House of the Dragon has already been confirmed for a second series.
Shortly after the first episode had aired, HBO announced the recommission in a tweet showing the programme's dragon logo with a blazing fire behind it, followed by a two.
It was captioned: "Fire reigns. #HouseoftheDragon has been renewed for Season 2."
The prequel series is set 200 years before the events of Game Of Thrones.It stars Matt Smith as Prince Daemon Targaryen, who is plunged into a bitter rivalry with his brother King Viserys (Considine) when the queen and their infant son both die, leading him to name daughter Princess Rhaenyra (Emma D'Arcy) as his heir rather than Daemon.
The series follows the history of the Targaryen dynasty and is shaping up to be just as bloodthirsty as Game Of Thrones.
Watch: Paddy Considine in House Of The Dragon