Wonder Woman is one of the most compelling characters in Batman v Superman: Dawn of Justice, and the hints about her backstory were tantalising. Instead of rushing around saving people, the Diana we meet in Dawn Of Justice is reserved, sneaking around Lex Luthor's mansion in civilian clothes. And she's not foiling Lex's grand plan but retrieving a photo to protect her secret identity.
All of this points towards a rather disillusioned Diana Prince who has given up being a hero, which was something Gal Gadot confirmed before Batman v Superman was even released.
So what happened in Diana's past that made her want to hang up the Lasso of Truth?
The Hesitant Hero
By the end of Dawn of Justice, Diana and Bruce Wayne agree to seek out the other metahumans, which will likely lead to them forming the Justice League. However, Diana's words to Bruce hint that even after helping defeat Doomsday, she is still uncertain about whether they should find the budding heroes.
"Maybe they don't want to be found."
After she spent most of the movie working to keep her identity secret from Lex Luthor, it makes sense that Diana would respect the metahumans' privacy. And yet, we know she'll come around to Bruce's way of thinking. After all, if she didn't there would be no Justice League.
We know that the main WWI-based action of the solo Wonder Woman movie will be bookended by present day scenes. So it's likely that Bruce these scenes will involve Bruce trying to persuade Diana to help him form the League, and her hesitance prompts him to ask her why she stopped being a hero. This would lead neatly into Diana recounting her experiences in World War I, which we know comprises the majority of the Wonder Woman film.
A Century Of Horrors
Diana's disillusionment about humanity makes a lot of sense in the context of her history: she is essentially a World War I veteran.
World War I was an incredibly traumatic and devastating time for most of the people involved in it. Although Diana "has trained her whole life for war", there's little that could prepare her psychologically for the horrific conditions of front line WWI combat.
Thanks to the Wonder Woman preview video, we've already seen scenes of Diana on the front lines of the war, and it seems highly likely that she'll lose many people dear to her. Coming from a utopian civilisation, where her fellow Amazonians have just as long a lifespan as her, this will no doubt be a huge shock to Diana. And considering Steve Trevor is the one to prompt Diana's entrance into our world, it could be his death which really pushes her over the edge, and convinces her that humanity's problems are too big to solve.
But Diana isn't just a veteran of WWI: we know from her cryptic allusions in Batman v Superman that she's lived through many more of our wars.
"A hundred years ago I walked away from mankind. A century full of horrors... Mankind made a world where standing together is impossible."
How many of these wars did Diana fight in? And how long did it take her to give up on humanity? It's easy to sympathise with her point of view: decades of being a soldier would leave anyone disillusioned about what they're fighting for, and whose side they should be on.
Hopefully, Wonder Woman will explore these themes, and the impact that Diana's longevity has had on her. Ultimately though, it seems as though the movie will emphasise Diana's her hope for a better future, as director Patty Jenkins explained.
"The best thing about Wonder Woman is how good and kind and loving she is, and yet none of that negates her power"
How this will all resolve remains to be seen, but it seems that even though Diana chose to take a break from being a superhero, ultimately her compassion drives her to take up the mantle of heroic responsibility once again.