"It's hard not to feel protective of her. She was so young," Kirsten Stewart said of portraying Princess Diana

Kristen Stewart is already feeling close to Princess Diana ahead of playing her in her upcoming film, Spencer.

The actress appeared on Jimmy Kimmel Live! on Tuesday night to promote her new holiday film, Happiest Season, where she touched on preparing for her role as the late royal in an upcoming biopic centered on the princess's last days before her death in 1997.

"I didn’t grow up with her maybe in the same way, I was really young when she passed away," Stewart said as she admitted to feeling "protective" of the royal. "I feel sort of the same way about her. It happened really quickly."

Stewart was seven when the princess died in a tragic car accident in Paris, saying all she could recall of the event were "the flowers" laid in front of Buckingham Palace in her honor.

"I was really young, [I] didn’t know what was going on," she said. "It’s hard not to feel protective of her. She was so young."

She continued, "I mean, everyone’s perspective is different and there’s no way to get anything right because what is fact in relation to personal experience."

"My movie takes place over three days, and it’s this really poetic internal imagining of what that might have felt like rather than giving new information," Stewart continued. "We kind of don’t have a mark to hit, we just also love her."

Kristen-Stewart, Princess-Diana
Kristen Stewart; Princess Diana
| Credit: Kimberly White/Getty Images; Tim Graham Photo Library via Getty Images

The film is expected to take place over three days as Diana realizes she needs to end her marriage to Prince Charles while spending Christmas at Queen Elizabeth's Sandringham estate in the 1990s.

In October, the actress opened up about how she's preparing for her highly anticipated portrayal of the late royal, particularly how she plans to nail the "intimidating" accent.

"We don't start shooting until mid-January. The accent is intimidating as all hell because people know that voice, and it's so, so distinct and particular," Stewart said in an interview with InStyle. "I'm working on it now and already have my dialect coach."

The Twilight star said she's also read several books about Princess Diana to help her embody the late icon.

"In terms of research, I've gotten through two and a half biographies, and I'm finishing all the material before I actually go make the movie," Stewart said.

"It's one of the saddest stories to exist ever, and I don't want to just play Diana — I want to know her implicitly," she added. "I haven't been this excited about playing a part, by the way, in so long."