Selma Blair's son helped shave her head ahead of her stem-cell transplant in one of the most emotional scenes in 'Introducing, Selma Blair'

• "Introducing, Selma Blair" follows Selma Blair's journey getting a stem-cell transplant.
• In a joyous moment in the film, Blair's son Arthur helps cut her hair.

"Introducing, Selma Blair" is an intimate portrait of the actress, who announced in an October 2018 Instagram post that she lives with multiple sclerosis (MS), and her journey to receive a stem-cell transplant. Along the way, the documentary is a joyous celebration of resilience with plenty of emotional moments, including one between Blair and her son, Arthur.

Although it has many moments featuring Blair's pain because of her MS, director Rachel Fleit told Insider and other members of the press in a round-table interview conducted via Zoom that Blair's story is "a story about human spirit and triumph and everything that comes with that."

One recurring theme in the film is how Blair grapples with how to make sure her son Arthur Saint Bleick, 10, doesn't feel stress because of her disability.

In the film, the "Cruel Intentions" star opens up about her complicated relationship with her mother, saying her mother "tethered a darkness" to her that made her believe "only my suffering could please her." Now, Blair says, she works hard to "break the cycle" with her own child.

"Even though he sees I'm not 100 percent well, I know he doesn't feel responsible," Blair says of Arthur in the film. "He can go and have a great time with his dad and he might only just have a glimpse of wondering 'Hmm, I wonder if mom's in bed right now.'"

To help Arthur manage his feelings about her diagnosis, she says she asked him what scared him the most about her stem-cell transplant procedure and when he said it was the idea of his mom losing her hair, she replied, 'Well then I'll just have you cut it so it's not so surprising to you.'"

Fleit captured the light-hearted moment in "Introducing, Selma Blair," and it marks one of the most heartfelt moments in the documentary.

Blair reflected also reflected on that scene in an interview with Entertainment Tonight. "That was pretty easy and a nice moment, and it makes me feel better knowing Arthur has a say - not a say, really, but is included," she said.

Despite the hair-cutting scene being a standout moment of the movie, Fleit told Insider that the most joyous day of filming for her was actually Blair's birthday party with family and friends, including Arthur. The celebration happens at the end of the documentary and goes by in a flash. But Fleit told Insider that "joy" was "palpable" that day.

"I remember thinking, 'Oh, you can feel the love here,'" the director said during the round-table interview. "Whenever I see the image of her blowing out the candles with Arthur and in the backyard and the dinner and everyone's sitting around and they're making a toast for her, I just think back to how much joy I felt and how much love I felt that day."

"Selma really has such a strong community surrounding her," Fleit added.

"Introducing, Selma Blair" is now streaming on Discovery+.