Filmmaker James Gunn returned to the world of the Marvel Cinematic Universe last week with the release of the Guardians of the Galaxy Holiday Special, his first foray into the MCU since 2017’s Guardians of the Galaxy Vol. 2. The special sees Guardians Drax, who is played by Dave Bautista, and Pom Klementieff’s Mantis travel to Earth in an effort to bring actor Kevin Bacon to the planet Knowhere as a Christmas gift for Star-Lord, who is portrayed by Chris Pratt. The special has earned rave reviews from fans both for its deep dive into the familial bonds between Mantis and Star-Lord and for cleverly weaving Bacon, who plays himself, into the wider Guardians of the Galaxy mythos. Gunn recently talked in-depth with fans on Twitter about the special, revealing details behind key character moments and how it fits into next year’s Guardians of the Galaxy Vol. 3.

One of the biggest topics Gunn talked about was Groot’s new look. As fans of the franchise know, the original Groot sacrificed himself in the first Guardians of the Galaxy film in 2014 only to be reborn as Baby Groot. The Groot in the special has transformed yet again into a muscular young adult that Gunn has dubbed Swole Groot. Fans of the series were quick to point out that Swole Groot is decidedly different in appearance than the original incarnation of the character. In discussing this change, Gunn notes that this version of Groot is an entirely different character from the one in the original film. Continuing, Gunn says that this version of Groot has lived a very different life than the original Groot, thus leading to their differences in appearance.

Gunn also says that the special allowed him to set up several elements of Guardians of the Galaxy Vol. 3 without having to do so in the film itself. By far the biggest element introduced in the special is that the planet Knowhere is now the Guardians of the Galaxy’s main base of operations. Currently, Gunn says that the team is trying to rebuild Knowhere after Thanos’ attack in Avengers: Infinity War. The special also introduced Cosmo, a talking dog who is a resident of Knowhere, as an ally of the Guardians.

The Guardians of the Galaxy Holiday Special is currently available for streaming on Disney+.