Davis was intimately involved in Houston's career and foray into film. While Houston was making the 1992 film, "The Bodyguard," with Kevin Costner, Davis saw a screener that he felt didn't showcase Houston's powerful pipes. He told Diane Sawyer in 2009 how he brought up the issue with the director.
"There was little, if any, music at all. I mean, her acting was decent. It was good, but it was not bravura," he told Diane Sawer. "I wrote a letter to the director and I said, 'You've got to go back, you've got to shoot again. We'll come up with music, we'll come up with great songs to show who Whitney is and what she is and why she needs to be protected by a bodyguard.' And the director at the time didn't get it. He fought it."
The director was fired and the film was changed in line with Davis' vision.
Though Houston reigned for more than a decade in film and song, with eight platinum albums and 55 million records sold in America, much of her enormous success fell away as her marriage to Bobby Brown descended into jealousy, rage and substance abuse. She endured multiple stints in rehab and divorced Brown in 2007 after 15 years of marriage.
But the years of drug abuse had taken their toll. The star's voice diminished, album sales declined and she was rumored to be near death because she looked so thin.
Davis orchestrated Houston's 2009 comeback after seven years of silence with the album, "I Look to You," which he called a labor of love. It sold 304,000 copies in its first seven days on the market, sending Houston back to the top of the charts and giving her the best debut week of her career.
Houston "still stands for the best of songwriting, the best of singing -- and we know the public wants it," he said in 2009. "There is a song on this album which is called 'I Didn't Know My Own Strength,' and it really speaks for Whitney. She tumbled but she didn't crumble."
ABC News' Sheila Marikar and Michele Major contributed to this report.