As a gay man with a disability, Daniel Monks is drawing on his life to find empathy for a child with unrelieved pain. In Sydney Theatre Company’s production of Lord of the Flies, the actor is playing Roger, a vocal and violent 11-year-old who appears to be a sociopath, enabling authoritarian rule over a group of boys who survive a plane crash on an island.

The actor has found allusions to Roger’s unspecified past trauma in both William Golding’s original novel and Nigel Williams’s stage adaptation, now being directed by Kip Williams. “In the play, Roger is the only character who refers to anything sexual in tone,” says Monks during a rehearsal break, the single walking crutch he uses on and off stage by his side.

“I’ve imagined, with Kip’s collaboration, that Roger’s come from a past of sexual abuse. I don’t think the audience will see that [back story]; it’s more for me to understand him, because he has a lot of pain and anger that he can’t reconcile, and his violence is a way of discharging that pain.”

Monks, 30, grew up in Perth. The son of a casting agent, he always wanted to be an actor but, at age 11, a physical education teacher noticed he favoured one side while walking. A botched biopsy followed, leaving him quadriplegic.

Monks began high school in a wheelchair, accompanied by a carer. But after neurosurgeon Charlie Teo removed a tumour from his spinal cord – “he saved my life” the actor says – and months of intensive therapy, Monks regained the use of the left side of his body. Some paralysis remains on his right side.

The physical ordeals occurred around the time he started to realise his attraction to other boys, compounding the pressure he felt on his sense of self.

“All the messaging I had from media and society was being gay and disabled were undesirable things,” Monks recalls. “You were lesser than your straight, able counterparts, and I had a lot of shame around it. Before I was out to anyone, I used to watch queer cinema and gay short films on YouTube, and that made me less alone in my struggle with my sexuality. But I never found that [storytelling] with disability, especially with young [actors] that felt real to my experience.”

Instead, Monks had to create his own. He was nominated for a 2018 best lead actor Aacta award for his role in Pulse – a film he also wrote – about a disabled teen who undergoes surgery to become a beautiful woman without a physical disability.

Lord of the Flies director Kip Williams says he had been wanting to work with Monks for years, having been inspired by the actor’s past performances. “He was excited to play a character in this piece who could be physical, strong and powerful, and so often he’s not given the opportunity to play roles of that nature.”

Casting Monks is not the only innovative choice Williams has made in this production. While Lord of the Flies is “usually described as being about the darkness that’s inside all of humanity,” says the director, “I see it as being about masculine cultures of power, and patriarchal power values, and how in the absence of adults these young boys play out ideas of masculinity. That is what generates the violence and dissent on the island.”

While the 1963 Lord of the Flies film adaptation directed by Peter Brook had a white male cast and is “generally considered to be a very accurate rendering of Golding’s novel”, Williams says his production of Nigel Williams’s script has “no white, able-bodied cisgender males” among his all-adult cast of 11 – a deliberate strategy to draw attention to characters “performing gender”; emulating fathers, uncles and other male leader role models.

Further undermining the notion that straight, white men should carve up power in the world, female actors play key boy characters. Contessa Treffone, for instance, whom Williams directed as pure-hearted Dolour Darcy in last year’s The Harp in the South, plays Jack, who violently opposes democracy. Film star Mia Wasikowska, in her first stage role, plays Ralph, the son of a naval officer who demands to be elected leader by vote.

Casting Treffone and Wasikowska as alpha males “speaks to the absurdity of how for many centuries we’ve had the same types of people occupy leadership roles”, Williams says. Broadly, the cast is also racially diverse. “There’s an irony in performing this play right now when we have a president in the White House who writes racist tweets, makes misogynist statements and can instigate transphobic policy and occupy that office,” Williams says, “and yet he was beaten by 3 million votes by Hillary Clinton.”

Monks hopes there will be more roles for actors with disability in future, given the current paucity of opportunities. In November, he will travel to London to star in the Mike Lew play Teenage Dick, a high school-take on Shakespeare’s Richard III, at Donmar Warehouse.

“Usually, there’s just no representation of disabled people,” Monks says. “Not seeing yourself and your place in society is hugely detrimental.

“I’m very interested in showing disabled people can be as many different types of things as possible – not only out of a desire for more interesting roles, but for wider society to see disabled people as more complex human beings, just like themselves.”

• Sydney Theatre Company’s production of Lord of the Flies opens at the Roslyn Packer Theatre on 27 July. Daniel Monks will be in conversation with Kip Williams at the theatre on 31 July