Groot speaks a language all his own that few understand, but in Avengers: Infinity War, Thor revealed that he was one of them. The reason he knows the language, however, is different than what he states in the film, according to filmmaker James Gunn.
"Thor was making a joke, as he is prone to do, when he said Groot was an elective [on Asgard]," the Guardians of the Galaxy director said when asked about the matter on Twitter. "Being a god of sorts he doesn’t have the same high bar for understanding Groot as the Guardians do."
Thor was making a joke, as he is prone to do, when he said Groot was an elective. Being a god of sorts he doesn’t have the same high bar for understanding Groot as the Guardians do. https://t.co/KG6GCqJZkX
— James Gunn (@JamesGunn) April 25, 2020
In a related tweet, Gunn was asked why Peter Quill couldn't understand the language, despite wearing a universal translator. "He doesn’t have a universal translator," Gunn said. "He has a translator. And it doesn’t have all languages in it (it didn’t have Sakaaran in the first film for example). And people don’t learn Groot through knowing the language - they learn it through connecting with Groot."
He doesn’t have a universal translator. He has a translator. And it doesn’t have all languages in it (it didn’t have Sakaaran in the first film for example). And people don’t learn Groot through knowing the language - they learn it through connecting with Groot. https://t.co/4PoUm2lXhv
— James Gunn (@JamesGunn) April 25, 2020
It can be inferred Thor's god-like status must give him a linguistic advantage then, as he proficiently understood Groot's language shortly after first meeting him, while most of Groot's teammates remain incapable of comprehending him without assistance.
In fact, outside of Thor and Groot's frequent companion Rocket, few if any have been shown capable of understanding the alien's tongue, which consists only of the phrase "I am Groot."
