[Very minor spoilers X-Men: Apocalypse ahead!]
As the third film in the reboot trilogy, X-Men: Apocalypse carries the weight of a vast franchise, bringing the plot back full circle by showing us the (new) origins of the core X-Men team from the original trilogy. That's a lot of responsibility for just one film and for the most part Apocalypse pulls it off, especially when it comes to Jean Grey and Scott Summers.
Although these two characters are two of the most important in the movies and the comics, they've both suffered being underwritten in the past. Jean struggles as much with being written as a useful part of the team as she does with her powers (those two things are probably interconnected), and Scott's always been a one dimensional douchebag. But that all changes in Apocalypse.
The Origin Story They Deserve
Apocalypse shows us Scott as a vulnerable kid rather than the arrogant team leader, which makes him a lot more sympathetic. And then there's Jean, whose struggle with her abilities makes a lot more sense for her age, and her narrative is ultimately far more satisfying than in the original films.
That's not to say that Jean and Scott were badly written in the original films, but they were difficult to root for. Scott suffered from being insufferable, and Jean just never really harnessed her abilities in a heroic fashion. It's really aggravating to see Jean just stand around in battle scenarios, when her powers are so incredible that if used properly, she's one of the most interesting characters in those situations.
There was always that excuse that her powers were just too powerful for her, but instead of using this to carefully explore Jean's development of her abilities, she has a few big moments that almost destroy her (and the less said about The Last Stand the better). Ultimately, any time Jean approaches the height of her power in the first X-Men trilogy, everything goes to shit.
Jean in the original trilogy is really interesting, and fantastically portrayed by Famke Jansen. But that's one of the reasons those films can be frustrating: we know Jean has awesome abilities, and we just want to see her harness that power to become the hero she was in the comics. So called "over-powered" female characters are often given the excuse of not being able to utilise their abilities because of the emotional and psychic stress, and Jean has fallen prey to that trope in the films so many times. Thankfully, Apocalypse finally breaks from this tradition.
The Leaders Of Tomorrow
The first of the original team we see in Apocalypse is Scott, as his mutant powers develop. A danger to himself and others, it's easy to empathize with Scott as he comes to terms with being a mutant. He's still a bit of a smart aleck, but there's a vulnerability to him that makes him interesting, both to the viewers and to Jean Grey.
The relationship between Jean and Scott is a tricky one. When we're first introduced to the characters in 2000's X-Men, they're already in a relationship which clashes with Jean and Logan's blossoming sexual tension. Because we didn't see how their romance began, Scott and Jean's relationship in the original films falls a bit flat.
But in Apocalypse, it's easy to understand why the two are drawn to one another. They're kindred spirits, both branded as outcasts even within the mutant community. Just as Scott's power can quickly injure others, Jean struggles with night terrors that rattle the walls, making her a pariah at the school. The two find solace with each other in a small way, and it's nice to see their relationship develop.
We get to see these young mutants come into their own in the final battle against the franchise's most powerful villain. This setts up a brave new future where Jean and Scott will lead the new, or in this continuity the first real X-Men team. Scott gets to unleash his laser vision, resulting in some of the most stunning special effects of the film. And then there's Jean, who finally (finally!) gets to be the hero we've always wanted her to be.
Moving forward, the prospects for this incarnation of the X-Men team are really exciting. Having seen how they began, we really care about these characters, and there's so much set up to develop both Scott, but especially Jean's abilities. Full of story potential, the post-Apocalypse future is bright - and it's shaped like a Phoenix.