As John Travolta and his wife, Kelly Preston, bid a final farewell to their 16-year-old son Jett Travolta today, Travolta's biographer remembered how Jett was the one subject Travolta rarely discussed.
"It was taboo, in the sense of not going into detail about his condition. It was one of these subjects that he didn't want to go into. And I had to respect that," Douglas Thompson, who has known the actor for more than three decades, told ABCNews.com.
That condition was Kawasaki syndrome, a rare disease the Travoltas say Jett developed at a young age. Jett Travolta died last week, the result of an apparent seizure, according to an autopsy report.
A private funeral service is scheduled to take place in the family's current hometown of Ocala, Fla., this afternoon, according to The Associated Press. Thompson speculated Travolta will draw on support from Scientology, the religion that has seen he and his family through tragedies in the past, as well as Ocala residents.
"He's been a Scientologist for many years, I'd imagine that would give him comfort now," he said. "It's controversial for some but the religion has done him well."
Travolta was introduced to Scientology by actress Joan Prather in 1975, according to Thompson.
"I was 21 when I first heard about [Scientology]," Travolta told ABC News' "20/20" in 1998. "And someone introduced it to me and they were so certain and happy, and I wasn't used to people being certain and happy. I was used to people being insecure and unhappy. I took a course and my life has never been the same."
He leaned heavily on his faith when his Diana Hyland, his girlfriend and co-star in "The Boy in the Plastic Bubble," was diagnosed with breast cancer in 1976. She died the following year at age 41 and Travolta turned to Scientology to cope.
"He turned down the Richard Gere role in 'American Gigolo' and found himself more and more drawn to the Scientology movement," Thompson recently told The New York Daily News.
In 2001, Travolta told CNN's Larry King that he used Scientology to deal with the deaths of Hyland and later, his parents.
"Life is overwhelming. Life is not easy. Life is tough," he said. "And you need something that really works and helps you actually, not promises to help you, then fail. And that's why I've always loved Scientology, because it offers help, and it works."
Preston, who has been married to Travolta since 1991, adopted Scientology before meeting the actor. In 2006, Rolling Stone magazine reported that Preston was introduced to the faith in 1985 by acting coach Milton Katselas.
She met Travolta in 1987 while filming "The Experts," and, according to a 1998 interview with Redbook magazine, was pleased to learn he was also a follower. Her devotion to Scientology grew stronger as she and Travolta grew closer.
"It's very much a spiritual science," Preston told People magazine in 1997. "It creates ways to handle everything, whether it's in your love life or in your work."
Celebrities have come out to support the Travoltas. Wednesday, Lisa Marie Presley, a follower of the religion, defended Scientology in a MySpace.com blog while expressing condolences over Jett's death.
"I am writing this because I have noticed that for the most part, people and the media have been very sympathetic and respectful, but there are those certain ones that want to use this horrible tragedy as an opportunity to once again, blame and-or attack Scientology."