Marvel’s Captain America: Civil War is technically a film about Steve Rogers, but given its gigantic roster of superheroes, it plays more like a very dysfunctional Avengers movie. Captain America and Iron Man lead warring factions of Earth’s Mightiest Heroes into battle against one another, but the two biggest bruises of the Marvel Universe — Thor (Chris Hemsworth) and Hulk (Mark Ruffalo) — are sitting courtside. But why? Well, just watch 2015’s Avengers: Age of Ultron.

Throughout Joss Whedon’s follow-up to 2012’s The Avengers, Bruce Banner struggles with guilt over the damage Hulk, his big green alter-ego, leaves in his path; that guilt is why he agrees to assist Stark in building the doomed sentinel experiment, Ultron. In a show-stopping mid-movie battle, Hulk — driven mad by Scarlet Witch’s mind bending — wrecks havoc in a South African city. Tony Stark, wearing his colossal Hulkbuster power armor, puts down the beast. But the damage is done. Hulk is a liability.

Moments after the final battle of Sokovia, Hulk heads off in a Quinjet, ignoring Black Widow’s pleas to come back. He shuts off contact and lets the Quinjet’s autopilot take him somewhere. Anywhere. Where he winds up is unclear. But he’s far enough away that they can’t find him in Civil War.

As for Thor, in Age of Ultron, the hunky viking foresaw a looming danger: Thanos and the Infinity Stones. But he can’t make sense of any of it and seeks Dr. Erik Selvig (Stellan Skarsgard) for help. There was an ample amount of deleted scenes cut where Hemsworth makes contact in the Norn cave and learns about the stones.

When Thor returns, he uses what he knows to infuse the Mind Stone — hidden in Loki’s scepter — with J.a.R.V.I.S., creating The Vision (played by Paul Bettany).

There are also legal reasons that involve fewer magic hammers and more strict corporate contracts. Universal owns the rights to a solo Hulk movie, while Mark Ruffalo says Hulk was actually written out of Civil War in an early draft. Chris Hemsworth has three movies left in his contract, one of them being Thor: Ragnarok coming in 2017 and Avengers: Infinity War being a two-parter.

But why wouldn’t they be in the movie if they were in the Civil War comic? Actually, that comic that the film is loosely based on sort of gave the filmmakers the whole idea. During Marvel’s Civil War published in 2006, Thor was dead and Hulk was busy being a space gladiator on an alien planet in a series titled Planet Hulk, written by Greg Pak. A Thor clone does show up to fight, so readers still got to see the Thunder God illustrated in the battle, but it wasn’t really Thor.

Hulk and Thor will reunite together in 2017’s Thor: Ragnarok, so anyone bummed about the absence of hunky vikings and gamma radiated ogres needs only be a little patient to see them again.

Captain America: Civil War will hit theaters on May 6, and Thor: Ragnarok is due out on November 3, 2017.