When Guardians of the Galaxy was first written, writer and director James Gunn wrote a separate script for Groot's voice actor Vin Diesel that included exactly what the lovable tree-like character was actually saying in his language. Gunn, who did some of the writing for the Guardians characters in Avengers: Infinity War, has now revealed what Groot's final line in Avengers: Infinity War actually was, and it's devastating. Warning: Major spoilers for Avengers: Infinity War lie ahead. Read at your own risk.

As we all know, the now iconic Guardian of the Galaxy Groot is famous for only saying the words, "I am Groot." As the first movie revealed, he is actually saying something in a different language that seemingly only his partner Rocket can understand. However, after the credits of Guardians of the Galaxy Vol. 2, it was revealed that Star-Lord had begun to learn what Groot was saying as well. Avengers: Infinity War went on to reveal that "Groot" was its own language, and Thor had actually learned it as an elective while studying on Asgard.

It is quite clear that every "I am Groot" actually has some deep meaning behind it, being very similar to Chewbacca's roars and growls in Star Wars. While not everyone can understand it, a spare few of the characters can and, most importantly, the cast, directors and writers can.

The end of Avengers: Infinity War featured half of Earth's Mightiest Heroes, and all but Rocket and Nebula of the Guardians of the Galaxy, disappearing into ash as a result of Thanos's success. The last we saw of our beloved Groot before he ceased to exist was him looking at Rocket fearfully, saying one final "I am Groot" before disappearing into thin air. His absence left Rocket completely alone and heartbroken, but what did Groot actually say? James Gunn has revealed that Groot's final words actually translated to one single word, which was:

"Dad"

This arguably makes Groot's death even more tragic and heartbreaking. Up until now, the two saddest deaths of the movie were most likely Gamora's and Spider-Man's, but this revelation takes Groot's passing to a whole new level.

As James Gunn revealed a few months ago, the Groot in the movies now is not the original Groot we saw in the first Guardians of the Galaxy, but rather his son. New Groot shares the same genetics as the original Groot, but is not the same character. Because of this, new Groot has been raised by Rocket and seen him as a father figure his entire life, as opposed to the original Groot who presumably did not meet Rocket until he reached adulthood.

Not only does the revelation show how terrifying this moment was for Groot, but it also shows how devastating it was for Rocket. His "son" faded into ash before his eyes. He murmured "Dad," terrified and asking his adoptive father for help, but Rocket could do nothing but watch as the boy he raised for four years disappeared.

It's little details like this tidbit of information from James Gunn that helped make Avengers: Infinity War into such a heartbreaking movie. Though it's very likely that we will see a majority of these heroes return in a year, the responses from those who remained like Tony Stark and Rocket couldn't help but make tears swell in the eyes of audiences around the world. Hopefully these will not be the last words we hear from Groot, and that next year he will be able to see his "Dad" once again.