Chris Cornell and Chester Bennington: How music forged friendship of two troubled rock stars

Among the first to express shock at Chester Bennington's apparent suicide on Thursday was Vicky Cornell.

"Just when I thought my heart couldn't break any more," Chris Cornell's wife tweeted after hearing that the Linkin Park frontman had been found dead in his home at the age of 41.

For the widow of the Soundgarden singer, who committed suicide in Detroit in May, the pain was far more than that of just a fan.

Bennington was a close friend of Cornell, who would have turned 53 on Thursday.

Fans were quick to note the timing, as well as the tribute Bennington had written in the wake of the Soundgarden and Audioslave singer's death.

“You have inspired me in many ways you could never have known," Bennington wrote in an open letter at the time.

"Your talent was pure and unrivalled. Your voice was joy and pain, anger and forgiveness, love and heartache all wrapped up into one. I suppose that’s what we all are. You helped me understand that.

“I can’t imagine a world without you in it. I pray you find peace in the next life. I send my love to your wife and children, friends and family. Thank you for allowing me to be a part of your life.”

Their friendship stretched back a decade and Bennington performed Leonard Cohen's "Hallelujah" at Cornell's memorial in late May.

They had become so close that Cornell had named Bennington the godfather of his 11-year-old son, Chris. 

"The Cornell family is overwhelmed by the heartbreaking news about Chester Bennington which tragically comes so soon after their family's own loss," said a Cornell family spokesperson.

"They open up their loving arms to Chester's family and share in the sorrow with all those who loved him."

Both men had their demons, battling drug and alcohol addiction. But their friendship was forged in music, sometimes appearing on stage together.

The singers bonded when they toured together nearly a decade ago.  Cornell opened for Linkin Park during a tour  of Australia in 2007, and through 2008 with Projekt Revolution, Linkin Park’s multi-genre tour and music festival.

When they performed on Cornell’s 44th birthday in July 2008, Bennington led the crowd in a rendition of “Happy Birthday”.

Cornell collaborated with Linkin Park while they played their 2000 hit song “Crawling,” while Bennington took to the stage during Cornell’s set to sing a cover of Temple of the Dog’s “Hunger Strike.”

“For me, I’m such a fan I think that’s the most important aspect of why I do what I do and how I do it. I’ve got to play with a lot of guys that I’ve grown up loving; I get to sing on stage with Chris Cornell. … I’m just like, ‘What world do I live in, ’cause this can’t be real?’ ” Bennington told Rolling Stone in 2008 during a joint interview.

In a 2011 interview with Collider, Cornell said Bennington introduced him to rock video games like Rock Band and Guitar Hero.

"I played it one time and it was the only time I got to play it. It was in Chester Bennington's dressing room from Linkin Park. He had it and he was like, 'Hey, let's try it,'" Cornell said.

"He was there and he and his wife were playing it and they were both good and having fun with it."