Groot spent most of Guardians of the Galaxy Vol. 2 in baby form, but in one of the sequel's mid-credits scenes, the popular talking tree was seen have grown into a "teenager," rocking an an age-appropriate attitude to boot. We've since learned that this is the size Groot will be during Avengers: Infinity War, and because he's in this adolescent period, he'll use the superhero team-up movie to find someone who can help him during these formative years. Terry Notary, the actor who is playing Groot on set, said the following:
I can't say too much about him, but he's coming of age, so you'll see the teenager find a mentor to look up to and to model himself after.
War for the Planet of the Apes actor Terry Notary, who revealed earlier this year that he's playing Thanos' right-hand man in Avengers: Infinity War, confirmed to Yahoo Movies that he's also playing Teen Groot in the movie, though you'll still hear Vin Diesel voicing the tree's trademark line, "I am Groot." Understandably, Notary was unwilling to provide specific details on what Groot will be up to during Infinity War, but evidently when he and the other Guardians join forces with the Avengers and this universe's other major superheroes, he'll meet someone who he can look up to during the conflict, and likely after it.
Because the Guardians of the Galaxy movies have largely been separate from the rest of the MCU, the only superheroes he's had any interaction with are the ones on his own team. The Guardians have now cemented themselves as a family following the events of Guardians of the Galaxy Vol. 2, but as we saw in Teen Groot's mid-credits scene, he's in that phase of his life where, just like a human teenager, he has no issue back talking one of his "parents," which in that particular instance was Peter Quill. So to meet other heroic individuals during Avengers: Infinity War will undoubtedly leave a significant impression on him.
As for who Groot will aspire to be like during Avengers: Infinity War, I suspect it will be The Hulk. Even though Marvel's Green Goliath has a penchant for property destruction, it seems like Groot would have an easier time relating to him than most of the other heroes residing on Earth, whether it's because they're both insanely strong or they both have a small vocabulary. But if Groot is looking for more conventional guidance, Vision is another character that comes to mind who could serve as a strong role model. Whoever this mentor ends up being, here's hoping that they do a good job of making is easier for the sentient tree to eventually transition back into Adult Groot.
Avengers: Infinity War hits theaters on May 4, 2018. Look through our 2018 premiere guide to find out when next year's other blockbusters will be released.