When you break it down, Thor's adventure with Rocket and Groot in Avengers: Infinity War is different than every other storyline in the film. While most of the narratives feature established characters meeting other established characters, the quest for the Thanos-killing weapon is different in that it has the God of Thunder and two Guardians meeting someone new: Peter Dinklage's Eitri. It's a curious outlier ultimately -- but interestingly it wasn't the only approach that the filmmakers mulled over. Co-director Joe Russo recently explained,
As is, Avengers: Infinity War finds Thor (Chris Hemsworth), Rocket (Bradley Cooper), and Groot (Vin Diesel) on a journey to Nidavellir, which is the realm where his original lightning-conjuring hammer, Mjolnir, was forged. As I recently learned in an email interview with Joe and Anthony Russo, however, writers Christopher Markus and Stephen McFeely played around with a few different approaches for that particular story. Namely, there was a version of the script that found Thor going to his grandfather -- presumably Bor -- in order to acquire the Stormbreaker axe and become an equal match for Thanos. It makes one wonder if the idea involved a visit to Valhalla, but sadly Joe Russo didn't elaborate.
In regards to the "one of these things is not like the other" situation mentioned in the opening paragraph, this approach to Thor's weapon acquisition would have actually made it fall in line with the Avengers: Infinity War plotlines. After all, Marvel Cinematic Universe die hards will remember that Bor -- father of Odin -- was briefly featured in the opening vignette of Alan Taylor's Thor: The Dark World. Had the production moved forward with the angle, one would hope that they would have brought back Tony Curran for the sake of continuity.
As explained by Joe Rosso, Thor's journey to get a new weapon is one of the most important in Avengers: Infinity War, as he is essentially set up to be reality's best hope against Thanos. The Mad Titan basically waltzes in and does whatever he wants throughout the film -- primarily collecting Infinity Stones -- and the audience is left with the lone hope that the God of Thunder will be the one to save the day at the end, as he almost does. Explained Joe Russo,
As we all know now, however, things didn't work out as planned -- and we're now left biting our fingernails furiously in anticipation of next year's Avengers 4.
Clearly next May can't get here soon enough -- but the good news is that you now have the opportunity to watch Avengers: Infinity War as much as you'd like. The film is now available for DigitalHD download, and if you're in the physical copy collecting game, you'll be able to find 4K, Blu-ray and DVD editions on sale August 14th.