For most of its runtime,Shang-Chi and the Legend of the Ten Rings isn’t all that concerned with connecting to the rest of theMarvel Cinematic Universe. But there’s one huge cameo that does the exact opposite. And does it to perfection.

To be clear: that disconnect does not hurtShang-Chi. The film’s commitment to carving out its own space in the MCU, rather than retreading familiar ground, makes it feel refreshing and unique.

That’s not to say thatShang-Chi doesn’t tie into past MCU films. In fact,the film does connect directly to one surprising Phase Two film — via a character whose appearance will, at first, probably confuse some audience members.

For those viewers, here’s everything you need to know aboutthat character’s inclusion inShang-Chi and the Legend of the Ten Rings.

Major spoilers forShang-Chiahead.

Why is Ben Kingsley inShang-Chi?

Around the Marvel film’s halfway mark, Katy (Awkwafina), Shang-Chi (Simu Liu), and Xialing (Meng’er Zhang) find themselves imprisoned in the Ten Rings fortress by Wenwu (Tony Leung). However, they quickly realize that they’re not the only ones being kept underneath the compound.

Sneaking over to one of the other underground cells, the trio finds themselves face-to-face withTrevor Slattery (Ben Kingsley), the fake-out Mandarin from 2013’sIron Man 3.We quickly learn Trevor has been a prisoner of Wenwu’s for years.

It’s an unexpectedly comedic moment, with Kinglsey bringing the same manic, drunken theatrical energy to the character that he did in bothIron Man 3 and the 2014 Marvel one-shotAll Hail the King. In a surprising turn of events, Trevor goes on to have a consistent presence throughout the second half ofShang-Chi, with him and his cellmate, a faceless magical creature named Morris, helping the film’s heroes to reach the realm of Ta Lo before Wenwu.

As a character, Trevor is totally unlike the other players inShang-Chi. Not only is he more farcical and outrageous, but he’s also one of the only characters inShang-Chi who has previously appeared in the MCU. Even more surprising: of the few pre-existing MCU characters who do show up inShang-Chi, Trevor has by far the biggest role.

But despite the unexpected nature of his return, his appearance inShang-Chi makes sense. Let me explain.

Trevor Slattery in the MCU

Kingsley made his debut as Slattery back in 2013’sIron Man 3, spending most of the film masquerading as “The Mandarin,” an international terrorist who broadcasts his crimes live on television. It’s eventually revealed, however, that Slattery isn’t actually “The Mandarin,” but a drunken British actor hired by Aldrich Killian (Guy Pearce) to pretend to be.

Notably, the use of Slattery in place of The Mandarin didn’t sit well with Marvel fans back in 2013. Many believed, rightly, that the Trevor character was just the result of Marvel wanting to avoid doing the necessary work of creating a version of The Mandarin that didn’t rely on the comic character’s problematic,racist origins.

But despite how poorly his role inIron Man 3 was received, Trevor was revisited inAll Hail the King, a 2014 one-shot that followed the disgraced villain as he was interviewed in prison about hisIron Man 3activities. Notably, that one-shot ended with Slattery kidnapped by an agent of the Ten Rings organization, who’d been sent to retrieve the actor by the organization’s actual leader.

Why Trevor Slattery is inShang-Chi

Now, eight years after the release ofIron Man 3,Shang-Chi and the Legend of the Ten Rings follows through on the promise ofAll Hail the King’s ending. Tony Leung’s Wenwu fills the role of The Mandarin in the MCU without falling into racist stereotypes — in one of the film’s best scenes, Wenwu even pokes fun at the Mandarin moniker — and stands tall as one of the best villains that the Marvel Cinematic Universe has seen.

The inclusion of Trevor Slattery inShang-Chi, meanwhile, serves two purposes.

Firstly, it wraps up the loose end created byAll Hail the King, revealing that Trevor was brought to the leader of the Ten Rings and, thanks to an improvised performance ofMacbeth, kept alive for several years in a cell underneath the organization’s mountain compound to serve as court jester. His role in the film also helps connect the plot ofShang-Chi to Marvel’sIron Man trilogy, which introduced the Ten Rings as an organization but never actually managed to feature the group (or its leader).

In other words, the film uses Trevor to help bridge its story and characters to the wider MCU.

That’s ultimately why he’s in the film. Mileage may vary as to whether this is a worthwhile reason for his inclusion, especially considering the outrageous presence he immediately brings toShang-Chi, but Trevor’s become an unexpectedly pivotal player in the MCU.

Shang-Chi and the Legend of the Ten Rings is playing in theaters now.