The 36-year-old actress reminisced in an interview with ABC News about her friendship with her late co-star ahead of the premiere of The Fate of the Furious.
"The reason I'm not [in Fate] is that Mia's with Brian, so I can't think of a better place for her to be," Brewster said of her character, Mia Toretto, who was last seen with Brian (Walker) and their son in Furious 7. "I imagine they're on some idyllic island living the life."
"I love Vin [Diesel], I love Michelle [Rodriguez] ... but my friendship with Paul was definitely the highlight," she added. "He was the best guy, just the best. The bond I had with him was definitely the best part of working on the Fast films."
Brewster starred alongside Walker in The Fast and the Furious, Fast & Furious, Fast Five, Fast & Furious 6 and Furious 7. Furious 7 was released in 2015 after Walker died at age 40 in November 2013.
"Paul was an enormous presence in my life for the past fourteen years," Brewster said in a statement after the actor's death.
"He lived with integrity, humanity and humility," she lauded. "I don't know anyone who lived each moment more fully and loved life more than Paul; making his loss all the more heartbreaking."
Diesel, Rodriguez, Jason Statham, Tyrese Gibson and Ludacris will return to star in The Fate of the Furious, which opens in theaters April 14. The movie released a new trailer this month that shows Diesel's character going rogue.