Why Nathan Fillion's First Meeting With The Rookie's Pete Davidson Left Him 'Ashamed'

Plenty of familiar faces have ended up getting on the case of John Nolan (Nathan Fillion). Kelly Clarkson's cameo on "The Rookie" had fans going wild when she crossed paths with one of television's most likable cops, and there have, of course, been occasions when Fillion's old on-screen crewmate Alan Tudyk and other "Firefly" stars had cameos on the show as well. Of all the stars who have come and gone, though, Fillion's favorite guest was former "Saturday Night Live" alumnus Pete Davidson, whose appearance came about from a genuinely humbling experience from their time together on James Gunn's "The Suicide Squad."

When looking over the impressive guest list that had unfurled in the lead-up to the 100th episode of "The Rookie," The Hollywood Reporter asked Fillion who took the top spot of VIP. "One of the people I had the most fun with is Pete Davidson, whom I met on 'The Suicide Squad," he said, recalling nothing but good things about the man behind Blackguard, who was brutally killed in the opening of the hit comic book movie. "When I first met him, I thought, 'He and I are probably not going to be best pals.' And within four minutes, I was embarrassed and ashamed because I'd judged a book by its cover. He's an incredibly kind man. Within two or three days, I invited him to do an episode, and he graciously accepted."

Nathan Fillion saw how 'wildly talented' Pete Davidson was on The Rookie

Turning up to show his face is one thing, but being able to deliver something of substance was a great surprise for Nathan Fillion when Pete Davidson appeared as Pete Nolan, John's half-brother. Initially appearing in Season 2, Episode 13, "Follow-Up Day," his character delivered enough that he returned in Season 4, Episodes 5, "A.C.H.," and 22, "Day in the Hole." Fillion has nothing but praise for his co-star, who — besides being who we have to thank for Joe Pesci's return to comedy in "Bupkis" — makes for a great on-screen sibling.

"He's wildly talented and always brings a flavor to the character that's realistic," said Fillion. "It's been a pleasure seeing what this unlikely friend of mine can do with being an unlikely half-brother and friend to my character."

Unfortunately, even with the big celebrations during Season 6, Episode 2, "The Hammer," the show's 100th installment, Pete Nolan is nowhere to be found. Instead, it is revealed by Skip Tracer Randy (Flula Borg, another of Fillion's co-stars from "The Suicide Squad") that he had to turn him in for unpaid parking tickets, which certainly fits the bill for John Nolan's half-brother. Fingers crossed that Pete gets his fines cleared up and returns to "The Rookie" somewhere down the line.