This is the story of a man who lost everything.

In his grief, rage and anger, he decided to burn it all down and start fresh, with something that was forever lost to him, something he could never obtain for himself: humanity.

This is the story of the evolution of a species.

The "divergent evolution" theme is uncommon, but not unheard of. It's been done before, in anime like and games like Civilization: Beyond Earth. This theme usually follows a "three sided struggle" approach between genetic modification, technological alteration, and the middle path that tries to stay true to the "human experience". In Beyond Earth this was Harmony, Supremacy and Purity, respectively. Those who have seen the aforementioned anime will know how each side is represented, as well. While we've seen hints of the middle path occasionally reveal itself over the course of DarliFra, it has not fully revealed itself... until now.

If we assume Darling in the FranXX's background conflict is the same, the plot rapidly begins to make sense:

    Klaxosaurs are humans that genetically modified themselves for life underground. As their evolution continued, they slowly lost their individuality in favor of hive-mind communication. They've exchanged higher functions like logic and reason in favor of emotion, instinct and enhanced senses.

    APE's society has gone in the opposite direction, enhancing themselves with technology and eschewing all "natural" parts of humanity, such as relationships and emotions, in favor of longer lifespans, digitalization, and an ultra efficient way of life.

In their abject hatred for their enemy, both sides have become something less than human. Both have thrown away too much. There is no longer any balance in the world and everything is distorted. Into this mix comes Werner Franxx, the man who is quite literally half-and-half, and the only human to ever have a relationship with a klaxosaur. He is our third path.

I am going to take a shot in the dark and try to guess the plot to Darling in the FranXX:

At some point before the series begins, the Klaxosaur Princess decides to leave the safety of her underground community and ventures out to explore the world. APE is not yet established, the klaxosaurs have only just begun their genetic modification, and people still use names. During her travels, she meets a curious, open-minded man named Werner.

The two hit it off immediately. Eager to be with him, the Klax Princess leaves her tribe for good and becomes Werner's partner. She brings with her one of the klaxosaurs' early biomechanical vehicles, something that would eventually inspire Franxx to make, well, Franxxs, and together they explore the world and delve into humanity's future together. Things are beginning to get tense between the two sides, but the couple is eager to find common ground.

Tragedy strikes, and the Klax Princess unintentionally brings Werner to the brink of death. Klaxosaurs and humans have diverged too much genetically and are no longer compatible. Werner is severely injured and partially saurified. Horrified at what she's done and thinking herself a monster, the Klax Princess vanishes without a trace, and Werner, being a normal human, is too injured to give chase. The biomechanical vehicle is abandoned and eventually seized by APE as it rises to power. It becomes the basis for Hringhorni.

Unable to pilot, Werner throws himself into the sciences and quickly rises up the ranks of APE as it's established. He remains fascinated with klaxosaurs and obsessed with his lost princess, but can do nothing due to society's intrinsic sociopathy and the prolonged conflict. Through his time spent with the Princess, now internally called Code: 001, Werner develops the Franxx mechs and begins experimenting on a side project: making his own Princess. APE approves of this project due to Hringhorni's importance; such a bioweapon would be valuable. Growing ever more disallusioned with APE's goals and missing the time he had with the Princess, Franxx buries himself in his work. The lifespans of both sides has been greatly increased - the klaxosaurs' by their genetic modification and APE society's through technology and increasingly advanced digitalization.

After years of trial and error, Werner succeeds in creating a lab-grown human-klaxosaur hybrid, who is given the code 002. In secret, he breaks APE's rules for the first time and creates something of cultural value - a fantasy picture book based on his time with the Klax Princess. He has it delivered to 002, hoping it will give her something to latch on to and keep her grounded. Testing begins.

Code 002 is broken out by one of the top students of the garden, Code 016. Werner reviews all known info on 016 and recognizes an uncanny similarity to his past self. The doctor sees an opportunity.

Upon successful retrieval of both 002 and 016, Franxx sedates them and runs tests. He identifies trace elements of klaxosaur blood within 016. Under normal circumstances 016 would be immediately disposed of, but instead Werner suppresses his memories and returns him to the Garden, watching his every step.

002's memory is only partially suppressed. Under the guise of memory alteration, Franxx instead embeds everything about the picture book into 002's psyche, to the point where she can redraw the entire book from memory. 002 has associated the picture book with her darling, and due to the embedding her life now revolves around finding him. APE, having been rid of emotion for a while now, sees no threat in this and easily manipulates 002 into thinking she'll be able to find her darling by killing klaxosaurs and becoming human. She is controlled. Development of Strelizia, modeled after Werner's memories of his Princess, begins.

Again in secret, Werner gives 002 a full education as she grows up... including education on sexual reproduction. Feeling an attachment to her for obvious reasons, he spoils her as any doting father would; she is the daughter he never had. But as she's grown, 002 has only become more obsessed with finding her missing beloved and blames herself for their separation. Thinking herself the only one of her kind and partly due to APE's manipulation, she concludes that she's effectively sterile and doesn't deserve anything until she becomes human enough to find her darling. She experiences intense periods of self-loathing and depression. She occasionally self-harms. Werner does what he can for her and gives her the space she needs. Internally, he hopes that the payoff will be worth it, and that once reunited 016's memories will unlock sooner rather than later.

As time goes on, Werner plots his next moves, carefully masked from the APE council. He uses the loss of Plantation 13's entire squad as a convenient excuse to assemble a test squad of candidates not only susceptible to "deprogramming", but who also have great personal attachment and/or loyalty to Code 016, who could eventually recognize him as their emotional and spiritual leader. Parasites who have the potential to live for themselves, but also act as the bodyguards of his "children". He designs custom Franxx models for all but 016, and makes sure to pair him with an incompatible pistil (rip Naomi). Code 016 fails to become a parasite, but due to his special status as Franxx's guinea pig is allowed to stay at Plantation 13 until his true partner arrives. A few days later, Werner arrives at Plantation 13 with both Strelizia and 002. APE grants the doctor permission to govern the Plantation 13 squad as his own experimental group, a testbed for "future soldiers". With no emotional intelligence, APE fails to recognize the obvious bomb sitting dormant beneath their feet.

The good doctor begins to meticulously cultivate the seeds he has planted, tracking their progress and monitoring Hiro's rising YBC levels and evolution intently. He makes adjustments when he deems it necessary and makes sure Hiro and Zero Two work through their issues. At times, he personally intervenes and corrects the course himself. Werner sees the biggest opportunity of all once Plantation 13 is disabled during the battle of the Gran Crevasse, and he quickly moves to completely cut the parasites off from both APE and the outside world at large. He watches, pleased, as they start becoming something different - not fully klaxosaur and not droneless pawns of APE. Something more, something adapted to the world around them. Something balanced.

Something human.

Eventually, the Nines arrive for a checkup. But they do not find willing parasites, ready to loyally sacrifice their vitality for the Priest-Kings. They find heresy, a disease that extends all the way to the Plantation's administration. And to their biggest surprise, Nine Iota isn't just a defector, but at the core of the rebellion itself.

The Nines rush back to APE, but it's too late.

Good scientists learn from their mistakes. Werner Franxx never forgot his. This time, the evolution of the species is protected. This time, the Prince and Princess have worked out their differences and become something more. This time, they have a Royal Guard for protection.

The fuse ignites.