The first drafts of Solo: A Star Wars Story saw Han and Chewbacca meet in a very different way. Rather than Han save Chewie's life, it was originally the other way round, with Chewie rescuing Han from a warzone.
Lawrence Kasdan first signed up to work on Solo back in October 2012, and the project changed shape quite radically over the course of the next few years. By April the next year, Lucasfilm began to commission concept art to support the film, and a wealth of that concept art is published in The Art of Solo: A Star Wars Story. Along with commentaries from the cast and crew, this gives an unprecedented glimpse into the behind-the-scenes development of the latest Star Wars film. Perhaps most excitingly, it reveals that the first scripts saw Han meet his Wookiee co-pilot in very different circumstances.
Chewbacca has traditionally served as a sort of "sidekick" figure for Han, but in the early drafts of Solo: A Star Wars Story he was actually a whole different type of partner. The two originally met on the front lines of the battle against the Empire, and Chewie saved the young Han's life - not the other way round.
According to ILM senior art director Aaron McBride, Kasdan's original story saw Han Solo become a pilot in a fleet resisting the Empire. Unfortunately, Han's cocky demeanor led to his making a critical mistake. In a scene styled after Top Gun, Solo crashed his damaged fighter into a hangar. This early script saw Han brought before a tribunal, who sentenced him to Mimban. There, he fought not as an Imperial soldier but against the Empire.
Han's army was imagined as one made up of countless alien races, all united in their opposition to the Empire. McBride explained that this version of Mimban would have been inspired by World War I trench warfare; "bleak muddy battlefields, burnt broken trees, and a sky overcast with smoke." Han and Chewie, who were partnered together, wound up going up against Imperial mech walkers. There, in an unexpected twist, it would be Chewie who rescued Han from Imperial fire, establishing an inverted version of the famous "life debt".
This would certainly have set up a completely different dynamic between Han and Chewie, both compared to the release version of Solo: A Star Wars Story and the now-Legends Expanded Universe. The Wookiee life debt has traditionally been portrayed as a code of honor that bound Chewbacca to Han's side. These early drafts inverted that, with Han initially the one who owed Chewie. Other early concept art in the book suggests the two would have saved one another time and again over the course of the film, with each becoming honor-bound to the other. It's an interesting approach, one that turns the life debt into a mutual experience.
The final draft of Solo doesn't actually mention the life debt at all. Instead, it presents the relationship between Han and Chewbacca as one based on real friendship rather than a code of honor. The life debt is still canon - it was discussed at length in Chuck Wendig's novel Aftermath: Life Debt - so it was presumably established later on in the two's partnership instead. In narrative terms, that's a far more satisfying approach, as it allows Han and Chewie to be presented as equals in Solo: A Star Wars Story, although an mid-battle rescue would have been more striking than a muddy cage match.