Richard Madden only looks 19; he’s actually 32. Still, it’s a little surprising to hear him describe the distance between his run as Winterfell scion Robb Stark on “Game of Thrones” to David Budd on “Bodyguard” as “moving on from being a son to being a father.”

“I’ve played Romeo twice onstage,” the handsome Scot says in a lilting brogue, “but I’ve kind of played incarnations of Romeo for the past 10 years in all my parts. So to move on to someone I really don’t see as a Romeo character, I’ve loved doing that.”

Sunny, smiling and lighter-haired than “GoT” fans will remember him, he allows that it’s still a bit of a whirlwind — “Bodyguard’s” rating success (setting viewing records in the U.K.) and honors (Golden Globe and Critics’ Choice nominations for him). His ex-soldier/now policeman assigned to protect the U.K. home secretary is indeed a young father, though that might not be the first quality that comes to viewers’ minds. Budd is a PTSD sufferer who experiences triggered rages and near-panic attacks. In moments of action, he’s at his best.

“If he’s saving someone else, it keeps him intact,” says Madden. “He can fix that. For a man who’s been through such trauma in his life to go straight back into a job like that, it’s repeating cycles.

“But that’s his purpose in life. When he stops doing that, he feels completely redundant. And all these other things he’s been pushing back start creeping up on him.”

That’s where the father-and-husband thing comes into play. Budd is, in his professional guise, stoic, efficient. But underneath are roiling waves that lead to some unprofessional behavior and outbursts that make it understandable why his wife wanted out of their marriage.

“That’s another thing about this, to not be scared of being disliked. Particularly in the scenes with my wife. Those scenes on the phone, there’s a certain — ” he takes on an aggressive harshness, “tone that I speak to her in that is horrible. It’s a way of speaking to someone that people will very much dislike. And I dive straight in because I thought it was important to understand. But then, when we see them alone, how much she means to him is conveyed, and that all ties into his PTSD.”

Budd and the show probably confound American audiences. He barely fights; many characters live in a gray zone between good and bad. It expresses some unusual points of view for a thriller. And Budd’s ultimate triumph may be that he stops denying he needs help.

“I read a statistic that 13 years is the average time it takes from someone having a traumatic experience to seeking help for PTSD,” Madden says.

“That’s a huge amount of time. And it festers and grows, and it can dominate your life and you don’t even know it.”

Madden already has 25 screen credits but allows that “Bodyguard” put him through his paces like no other project so far.