Heath Ledger’s Private Side Comes Alive in Revealing New Footage: It’s Like He ‘Pieced It Together’ for Daughter Matilda

He was a blazing talent who stunned audiences with his portrayal of a conflicted cowboy in Brokeback Mountain and the Joker in The Dark Knight. He was the doting father to his “darling” daughter Matilda, and he was the loyal son and brother who would come home to his native Australia and cover the ceiling in flour as he made pasta from scratch.

Now, nine years after Heath Ledger‘s 2008 death at age 28 from an accidental overdose, those closest to him open up to PEOPLE in this week’s cover story about the late star’s private side — and discuss the evocative, never-before-seen video footage that sheds light on the Oscar winner’s soulful inner life.

Related: The ‘I Am Heath Ledger’ Trailer Is Out, and Our Hearts Are Broken All Over Again

His sister Kate tells PEOPLE that in some ways the “beautiful” upcoming Spike TV documentary I Am Heath Ledger, set to premiere on Spike TV on May 17 following its debut at the Tribeca Film Festival on April 23, is Ledger’s final gift to his now 11-year-old daughter. (The documentary will also have a limited theatrical release on May 3.)

“You can tell her about things, but with her being able to visually see his movement and his expressions, it’s almost like he had actually filmed the documentary himself and pieced it together for her,” she says.

Kate opens up about “the extremely active young boy” who grew up in Perth, Australia, where Heath would gaze at the glow-in the-dark stars on his ceiling and debate whether to be an actor or hockey player.

Acting won out, and filmmaker Matt Amato, one of Ledger’s closest friends, recalls the natural confidence he brought to Hollywood from the outset.

“My friend had just written 10 Things I Hate About You and they were just lacking young actors to read for it,” he recalls. “I talked to my friend who wrote it and said, ‘This kid is staying here, and he’s unemployed and no one really wants an unemployed roommate.’ I was quickly developing a scheme to get him moving … The next day he said, ‘I like your friend’s script. I would like to play Patrick.’ That was the lead. It kind of dawned on me who we were dealing with right away … I didn’t discourage him, I just kind of came to my own conclusions about his confidence and his ambition — that it was well placed.”

Despite Ledger’s initial eagerness for fame, as his profile rose his ambivalence toward his star stature grew. Childhood friend Kane Manera says Ledger hoped his friends would “ignore” his fame.

“There was the movie star and then there was the person, and they just happened to inhabit the same body but they were not the same person,” says Manera.

Longtime agent and friend Steve Alexander says Ledger loved “disappearing” into a role — and pals say his long-term ambition was to direct — but adds that the star felt less at ease in the Hollywood glare, which is evident in the documentary.

“There is this great footage that he seems to have taken himself [that shows his] playful, artistic side,” says Alexander. “But when you see him in the red carpet events, he doesn’t look as comfortable.”

Later, Ledger found a companion who could understand and relate to his experiences: Brokeback Mountain costar Michelle Williams.

“He was totally smitten with her and couldn’t wait to bring her home,” says Kate Ledger. “We all instantly loved her too, so it was great.”

The couple welcomed daughter Matilda in 2005, and friends and family say Ledger was a doting dad who instantly tried to empathize with his newborn daughter.

“He was a natural, he knew what to do with a baby right away,” Amato says. “I said, ‘How come you are so comfortable with this?’ He said, ‘Well, I look at her and try and be her and try to understand what she needs.’ ”

“I hope she remembers the way he would spin her around and call her darling and her excitement seeing him,” he adds. “They really did have something wonderful.”

Matilda was only 2 years old when Ledger died, and for those closest to the star, she remains his greatest legacy.

“Everything she does, her movement I suppose, reminds me of Heath,” says Kate. “I think the first five years after Heath passed, every time I’d see Matilda [I] would be in tears. Now, I am really happy that I am at a stage that I can see Matilda and be happy and feel her daddy’s energy through her.”