WARNING: This article contains spoilers for Shang-Chi and the Legend of the Ten Rings. The Marvel Cinematic Universe has been extremely successful no matter what your definition of that success is. But even a franchise as successful as the MCU will make some missteps along the way. For Marvel, none are as glaring as Iron Man 3's Trevor Slattery.
When it was announced that Ben Kingsley had been cast in the role as the Mandarin, people were extremely excited. An actor of Ben KIngsley's caliber, after all, should be able to bring a certain gravitas to the character that would ground it to the larger universe. And then came the swerve. It turned out that Slattery was not, in fact, the Mandarin at all, but a down on his luck actor who had been coerced into portraying the role. Fans were upset at the swerve, some going so far as to decry the actor even though he was his usual excellent self.
When last we saw Trevor Slattery in the Marvel One Shot All Hail the King, he had been kidnapped by the Ten Rings. Now, after more than eight years since he last appeared in the MCU, Slattery has popped up in Shang Chi and the Legend of the Ten Rings. When he appears, we learn that Slattery has been a prisoner of the Ten Rings this entire time, having been turned into a jester for the organization by Wenwu (Tony Leung).
But Shang Chi serves as something of a redemption movie for Slattery. The actor is in a position to help the titular character (Simu Liu) in his quest to find the mystical realm of Ta Lo. He is even present during the final battle, although in true Slattery fashion, he uses his acting abilities to play dead so he does not have to fight. Still, his actions during Shang Chi are likely to improve the viewers' outlook on the character overall.
While Shang Chi does not specifically set up any future appearances for the character of Trevor Slattery, it nonetheless sets the character up for the possibility to appear. Freed of the Ten Rings, Slattery is last seen in Ta Lo with his mystical sidekick, Morris. It's a good bet that, at least for now, that is where he will stay. It is worth remembering that, regardless of the fact that he was kidnapped, Slattery is an escaped convict in the eyes of the United States government and would likely end up behind bars should he return to the USA.
So where could he reappear in the future? Well, the most obvious answer, of course, would be Shang Chi 2 if Shang Chi were to return to Ta Lo to learn more about his abilities. Another option would be Doctor Strange and the Multiverse of Madness. Strange and Wong could find themselves in Ta Lo during the course of the movie. Other options would be few and far between, however, considering the difficulty in reaching Ta Lo.
The most likely answer, however, is that this is the end of Slattery's story. The Mandarin twist has been resolved with the introduction of Wenwu. The kidnapping from All Hail the King has been resolved. Slattery is safe. Were this to be the end of Slattery's story, it would be a satisfying conclusion to what many consider to be an unsatisfying beginning to a character. The writers have found a way to redeem a character that many thought was unredeemable. Shang Chi and the Legend of the Ten Rings is in theaters now.