ichard Madden says "Bodyguard" was inspired by a real-life affair between a Government minister and their Personal Protection Officer.
The 32-year-old actor played Sergeant David Budd in the hit BBC series - a bodyguard who has an affair with the woman he's protecting, Home Secretary Julia Montague, played by Keeley Hawes.
Richard explained that although many believed the relationship to be "very fictionalised", military advisers - who worked on BBC cop series "Line Of Duty" - revealed to him that in their experience "sometimes lines get muddied" and individuals end up in "different relationships" with their employees.
Speaking to The Los Angeles Times newspaper, the "Game of Thrones" star said: "To prepare for the role I worked with a lot of military advisers on "Line of Duty".
"People said it was very fictionalised, this relationship with the Home Secretary. But from them, without naming names, they said actually you do end up very close to these people and sometimes that line does get muddied and you end up in different relationships.
"It was interesting to know it was based on these protection officers who spend more time with their person than with their husband or wife and sometimes the line does get crossed."
As for what's in store for season two of the show, the "Rocketman" star says producers want to "create something different" although he will still be "part of the story".
He said: "We hadn't intended to make a second one but the character is so fascinating.
"We want to create something different and do justice to season one. I will be part of the story. I want it to be as exciting as season one and to show something new."