It’s been a rough “Homeland” homecoming for Peter Quinn.

The ex-CIA operative — played by British actor Rupert Friend — was left partially disabled (physically and verbally) and brain damaged after his sarin-gas poisoning last season at the hands of Berlin-based terrorists.

In the Showtime drama’s sixth season, Quinn has withstood an exhaustive laundry list of physical and emotional trauma. He’s battled drug addiction. He’s been shot (several times), beaten (several times), thrown into solitary isolation, beaten again and suffered seizures. In last week’s episode, Peter watched in horror as his ex-lover Astrid (Nina Hoss) was executed in cold blood — then faked his own death by holding his breath (underwater, in a lake) for an ungodly amount of time.

“I think Quinn is, in some ways, a cipher for resistance,” says the affable Friend, 35. “There’s something about him that’s like, ‘Test me. Test me again. Test me harder and I will come back stronger.’ You might think [what he’s gone through] is sort of fantastical at times, but nothing is impossible in what he does. I know this because I went into that lake at 6 a.m. on a December morning when it was like 10 degrees outside and I had to hold sandbags to weigh me down (under the water).

“There’s nothing superhero about Peter,” he says. “He doesn’t fly and he doesn’t have a cloak.”

Since joining “Homeland” in Season 2, Friend has seen his share of injuries — not as brutal as those that have befallen Quinn, but still …

“I’ve sprained my ankle twice and broken my foot once,” he says. “I had a squib [a small pyrotechnic device] go off in my face this season, which is a bit like somebody striking 100 matches into your face. I had very bad facial burns; it’s like being blinded, deafened and burned all at the same time … I’ve jumped through windows and cut myself.”

When “Homeland” wrapped last season, Quinn’s return was not a given — especially since it appeared that Carrie (Clare Danes) put him out of his misery as he lay near death in a Berlin hospital.

“This is a show rooted in reality, not fantasy, so I think everyone knew that if Quinn was going to return, you’d have to respect everything that had befallen him,” Friend says. “The first thing I heard [from the show’s writers] was that, ‘He’s markedly different, yet recognizable. He’s completely different but sort of the same.’ I don’t think the writers knew the state of Quinn’s mental or emotional state. The idea of taking a known and lovable character and 180-ing him in Season 6 was hugely daunting. But I wanted to do justice to his condition, to the truth of what happened, and not take short cuts.”

Friend says he did “some quite gruesome research” about the effects of both sarin gas poisoning and strokes — including talking to an expert in chemical warfare, a neurosurgeon who treats returning vets and watching “some upsetting YouTube videos out of Syria.”

There’s nothing superhero about him. He’s just a badass in some respects and I love him. - Rupert Friend on Peter Quinn

“For me as an actor, as somebody who hasn’t had a stroke, I was interested in the practice of, how do you take a bath or open a can of Jello or how do you load a gun or drag a body across the floor,” he says. “I had to make a lot of it up. There was a lot of ‘umming and aahhing’ [by the writers/producers] about how to do that, so I just had them shoot a video of me doing that stuff the way I wanted to do it and they said, ‘That’s great!’”

So what can we expect from Quinn as “Homeland” heads toward its April 9 season finale?

“What you’re going to see is the true character of the man,” Friend says. “There will come tests and decisions and actions that will really reveal him to himself — and unequivocally to the rest of us. He’s just a badass in some respects and I love him.”

“Homeland” 9 p.m. Sunday on Showtime