It was one of the strangest relationships in pop history - the therapist who took complete control of Beach Boy Brian Wilson's life when he was at his weakest.

Eugene Landy was portrayed as a manipulative monster in John Cusack's 2015 movie Love & Mercy.

But his son Evan told the Daily Mail his father should actually have been given credit for prolonging the life of the troubled Good Vibrations star.

Evan revealed the untold story of the musician's bizarre relationship with his controversial therapist.

Himself employed as part of Wilson's care team, Evan opened up about the music genius's darkest hours and revealed a side to Wilson his fans never saw.

He said that far from being the true Brian Wilson story, Love & Mercy was 'revisionist history' by the star's second wife Melinda.

The comments, made in an interview with the Daily Mail in 2015, come as it was announced on Wednesday that Wilson had passed away at the age of 82.

Eugene Landy (pictured in red) and Brian Wilson (in the white shirt) made repeated visits to Hawaii. This was the first of 16

Grossly overweight and addicted to drugs, Wilson was on the 'verge of death' in a Los Angeles hospital bed in late 1982 when Eugene was asked to step in.

Describing the tragic scene, Evan said: 'Brian was on deathwatch, he was so incapacitated he would light cigarettes and drop them off the edge of the bed and urinate and defecate. He was just reverting to being a baby.

'He was very heavy, he was absolutely at the peak of his addiction, of his weight gain, all of it. They brought my father in to save Brian's life.'

Evan, then 21, was tasked by his father with keeping an all-night vigil at Wilson's hospital bed to stop him setting fire to it.

He recalled: 'They were detoxing him there in that room. The hospital let him smoke and he would sit there light them, take a couple of drags and just drop them.

'I had to watch him overnight to make sure that he didn't light the room on fire.'

Landy is pictured with Brian Wilson as his controversial '24 hour therapy' was under way

Landy had been rehired as Wilson's psychotherapist after a previous stint in 1975-76 had ended badly with disputes over money.

Landy put Wilson on an infamous '24-hour therapy' regime, which included dousing him with cold water in the morning, padlocking the fridge and putting him on a rigid diet and exercise regime.

Describing the therapy in a 1981 handbook, Landy wrote: 'The success of 24-hour therapy rests upon the extent the therapeutic team can exert control over every aspect of the patient's life… gaining complete control over every aspect physical, personal, social and sexual environments.'

Landy was charging $420,000 a year, before expenses, and employed helpers, carers and bodyguards to be with Brian continuously, including Evan.

By 1985 Wilson looked healthier and happier then he'd been in 20 years but despite Landy's success the star's inner circle felt marginalized and that the doctor of psychology - not medicine - was pushing his over-arching influence too far.

It was during these years Evan forged a close bond with the star, living in his guesthouse, sharing many hundreds of meals, and even holding joint birthday parties.

He said: 'Predominantly what I did with him was go to movies with him and eat sushi with him, we went to amusement parks, and we did adventure stuff together. We went out and palled around and that was basically it.'

Along with Wilson, Landy's unique methods won him a host of famous clients including Alice Cooper and actors Richard Harris and Gig Young. But the psychotherapist was eventually discredited, losing his license amid a backlash over his treatment of the Beach Boy.

Evan Landy (right) spent years with Wilson while his father Eugene was his psychotherapist

In the movie Wilson's second wife Melinda Ledbetter – played by Elizabeth Banks - is depicted as his savior who managed to extract Wilson from the evil clutches of the domineering shrink.

It showed a menacing Landy, played by Paul Giamatti, telling Melinda, Wilson is a 'very, very sick man', violently grabbing food off him and shouting: 'Jesus Christ you are not hungry, you think you're hungry'.

But that's not how Evan recalled their relationship.

'I think he absolutely loved Brian. I don't think he would have invested that much time, energy with him if he hadn't,' he said. 'Brian was the never-ending topic of conversation.'

And while he describes his father as 'flawed', Landy insists he had Brian's best interests at heart.

'I do believe that his intention was always to help Brian and that he had a true love for Brian.

'I don't think he had a malicious intent against Brian, I don't think anyone could. Brian was such a sweet guy. He's incredibly kind, sweet and generous of spirit.

'He was literally this man-child, you spent anytime with the guy you had to like him because he had this exuberance that you only seem to find in incredible youth.'

Wilson is pictured with the Landy family and friends - Alexandra Morgan, Eugene, his son Evan and an unnamed friend

Wilson died this week aged 82, leaving behind a historic legacy - including founding the Beach Boys.

It came just a year after his wife Melinda died and less than a year after he was diagnosed with a neurocognitive disorder similar to dementia.

His children announced Wilson's death on the singer's official Instagram page this Wednesday, alongside what appeared to be a recent photo.

'We are heartbroken to announce that our beloved father Brian Wilson has passed away. We are at a loss for words right now,' they wrote.

'Please respect our privacy at this time as our family is grieving. We realize that we are sharing our grief with the world. Love & Mercy.'