Contains spoilers for Avengers 1,000,000 BC!
As cosmic heroes, the Guardians of the Galaxy have encountered countless alien races, and yet few have been as inherently powerful as the Flora Colossus Groot - now, Marvel explains why, as the alien lifeform is connected to the God of Thunder himself, Thor Odinson.
The Guardians of the Galaxy's Groot is an exiled Flora Colossus from Planet X - the second major Marvel character to bear the name, after the planet's evil ruler Groot who first appeared in Tales to Astonish #13. Despite appearing to simply be an arboreal lifeform, Groot is actually staggeringly powerful. Not only does he possess incredibly control over all forms of vegetation and a staggering healing factor, but he was also recruited as the ultimate weapon of the Gardener - an Elder of the Universe assigned to protect one of the Infinity Gems - and only recently proved able to trap a god within his mind when the Guardians faced Zeus' Dark Olympians.
Related: Groot's New Mech Armor Turns Rocket Into A Perfect Guardians Weapon
In Jason Aaron, Kev Walker, Dean White, and Cory Petit's Avengers 1,000,000 BC, fans finally get an explanation for why Groot is presented as so powerful and unique. As the story recounts how the Phoenix intervened in the relationship between Odin and Thor's biological mother Gaea, the Elder God notes that she has had many children, most of whom are deities or even cosmic entities, noting that one was a talking tree. Given how unique the Flora Colossi are suggested to be in Marvel lore, it's as close as possible to a sure bet that Gaea is the original mother of the species that resides on Planet X, and of which Groot is a member.
That's not necessarily to say that Groot is the direct son of Gaea - it's far more likely his original namesake is her son - but since Groot's species appear to procreate by budding off near-identical duplicates, it seems little of this divine provenance has been lost over the generations. Since Gaea is also the mother of Thor, this would make Groot the Odinson's nephew (if not half-brother), which actually serves to answer the mystery of Groot's incredible power levels and ability to go toe-to-toe with divine beings. Interestingly, Aaron and Chris Sprouse's Thors saw an alternate-reality Groot become worthy of Mjolnir and take the 'Thor' mantle, suggesting the writer has envisioned a link between the two for some time.
Groot wouldn't be the first god to join a Marvel team - and isn't even the only divine being on the Guardians' current roster - but the strong suggestion that he's directly descended from Thor's mother Gaea answers longtime fan questions about why a random alien has been so able to hold his own against gods, cosmic beings, and Infinity Stones. Taken as a whole, this is a rare occasion where a seemingly left-field twist actually ends up making a character make more sense, as Groot's link to Thor justifies years of Marvel's Guardians of the Galaxy stories treating him as a god in all but name.
Avengers 1,000,000 BC is available now from Marvel Comics.