AN: I had this idea in the middle of the night while half-asleep, so if you think it's riddled with plot-holes and makes no sense, you're probably right. Also, in my personal canon, Nausicaa got her jungle room up and running again and became a celebrated scientist-healer.

Canon: Much as I wish I knew the Nausicaa manga canon well enough to use it, I don't, so this loosely uses movie canon. For Naruto, it's manga canon, except for the inevitable AU.

Disclaimer: If anyone thinks I actually own Nausicaa or Naruto, they should take a holiday from the Internet and rediscover that pesky thing called Real Life. Also, the gorgeous cover image is by kaseyu on deviantART – go check them out!

Umino Iruka, taken a certain way, means 'dolphin of the sea'. Sea names are not the fashion in Konoha, where naming has two themes, if any: forests and fire.

In the Valley of the Wind, sea names are common.

Iruka's grandparents were both citizens of the Valley, born and raised. Their parents had been old enough to just about remember Princess Nausicaa, the beautiful, the brave. Iruka's grandparents had been raised on stories of her courage and her wisdom. Every child of their generation could recite you her life story.

Their son, Iruka's father, married a daughter of the Valley named Lastel. Her grandmother had been a little girl when the Tolmekians came to invade, but old enough to remember the story Nausicaa told, afterwards, of the dying Pejite princess who had tried, even with her dying breath, to make sure that the giant warrior was destroyed and the Valley protected.

Both of these stories made their way down to Iruka, when the time came.

Very few people in Konoha know of Iruka's brilliance with a sword.

He doesn't practise the style favoured in Konoha, where the sword is simply a weapon, a tool to be used. Swords are often the favourite of the Uchiha, but the Uchiha will always hold their Sharingan, first and foremost, as their chosen weapon. In most other shinobi a liking for the sword is considered odd, and – by the time Iruka learns – old-fashioned, which is why it isn't taught much.

In the style Iruka uses, the sword is an extension of yourself: of your breath, your will, your spirit. It's the style that could – just theoretically – allow you to swiftly and mercilessly kill the Tolmekian soldiers in your father's room with nothing but a sheathed sword.

That particular story found its way to Iruka, too.

Not many people, even shinobi, realise just how long the Third Shinobi War lasted. Hatake Kakashi, the prodigy who would later take part in it, was born during it; so was Uchiha Itachi. When Iruka's parents first travelled to the newly-discovered Hidden Continent, it was just beginning.

It was, in fact, an accident involving a Kumo jounin, an ill-chosen jutsu, a source of geothermal energy and the combination of lightning and water that, besides really kicking off the war, ensured that Iruka's parents would never be able to go home. Umino Iruka was born in Konoha, mostly because his parents liked the trees there and were aware that it was probably the only Hidden Village that would take in refugees.

Almost no-one alive now, in the Valley or out of it, knows that Lord Yupa had a cousin. Iruka himself doesn't know that she was his great-great-great-grandmother.

Unlike most children in a Hidden Village, Iruka was always well aware of the importance of civilians. His parents – both of whom had been trained to fight in the Valley – were officially shinobi, but they rarely took missions, and actually ran a small business most of the time, making up their obligation to the village by keeping the Intelligence department informed of happenings in the business world.

Besides, Iruka had been raised on stories of a land in which civilians were everything. Soldiers might be useful in an invasion, but farmers and engineers, foragers and explorers, and scientist-healers like Princess Nausicaa had been – they were the ones who kept the Valley alive. The Tolmekians, he was told, had underestimated the civilian Valley-dwellers, but who was it had rallied together to burn down the infected trees before they could poison the Valley? Not – this in a very dry tone of voice – the Tolmekians.

Iruka didn't become a shinobi because he thought it was a better occupation than being a civilian. He did it because he wanted to protect them.

After the Kyuubi attack, Iruka felt completely cut off. His parents were gone. His last link to his distant homeland was gone. He had always been subtly different, thanks to his upbringing, and now he was desperately alone. He compensated by pranking, by being the class clown. When something hurt, he laughed it off, mocking himself without mercy. After all, there was no-one left to comfort him anymore.

It was the Sandaime who recalled him to himself, who brought him to his senses. After that fateful talk, Iruka remembered all the heroes and heroines of his childhood, who had worked through their own pain to protect the Valley and all that they held precious, and swore to stop living in his grief and start protecting others from the same.

At first, when Iruka looks at Uzumaki Naruto, all he can see is my parents, dead, Konoha in flames, the end of my ten-year-old world. He dragged himself out of that mire of misery and anger and now here is this child bringing it all back, it isn't fair. It isn't in Iruka's nature to be cruel or unfair to the boy, but he comes perilously close.

Then one day, when he's coming up to the Sandaime's office to talk to him about something (the curriculum, maybe, or the policy for Hyuuga prodigies and Iruka's objections to it), he hears the old man shouting louder than he's ever heard, telling someone that Naruto is a boy, he will not be terminated, he will not be turned into a weapon, he is a boy and god help me I will protect him to my last breath!

The next time Iruka looks at Naruto, he remembers the story that starts: When Princess Nausicaa was only a little girl, out in the fields one day, she found a baby ohmu…

That day, he praises Naruto's contribution in class for the first time.

With his skill, Iruka could have made special jounin. He could even, with no life outside training and a whole lot of B-ranks under his belt, have made jounin. Contrary to what most people think, he chose to remain a chuunin.

For most shinobi the next rank up is an aim in itself. No genin, certainly, cares much about the increased danger and responsibility that comes with the rank of chuunin – or rather, most of those that take the chuunin exams don't. Theoretically, those who pass should be the ones who do care; in practice, only a few fit that particular criterion. More thought tends to be put into taking the jounin exams, but the rank of jounin is still what tends to attract the examinees.

Iruka looked at the missions (he does work on the mission desk, so he can't avoid it), and – illegally – at some of the reports of the official shinobi therapists: not any specific, personal ones, but general recommendations and problems. Then, very deliberately, he took the application form for the jounin exam and put it through the shredder.

Iruka was raised on stories of Princess Nausicaa, the pacifist princess who fought to save her people, and he knows that a good defence doesn't have to mean offence.

When the Sandaime praises Iruka's understanding of the Will of Fire for the first time, Iruka finds it ironic.

He never thought of fire as something that could protect. The people of the Valley follow the ways of the water and the wind, his mother always told him. The water and the wind can keep the air clean and the plants safe. The water and the wind can heal barren ground and grow a forest. Fire can only destroy.

But he remembers the story of how the people of the Valley were forced to burn down their own trees to keep the soil and the water from being polluted, and he thinks maybe he understands: the Will of Fire is the will to protect your own by stopping the poison – whatever it may be – before it can reach them.

He doesn't forget the water and the wind, though. Nor does he forget how the people of the Valley grieved.

When Iruka and Naruto have grown closer, and are walking back to Iruka's apartment, one night, Iruka finds himself telling Naruto the story of Princess Nausicaa.

It's a long story, and somehow Naruto ends up on Iruka's worn old sofa, as Iruka tells him about Yupamiralda, the legendary swordsman, about old Mito who flew the gunship, about fierce Kushana the general, about Asbel, about Teto – of course Naruto latches onto that part – and about Lastel. They stay up so late talking that Iruka sets up a makeshift bed for Naruto in his living room.

When Naruto wants to know where the story comes from, Iruka tells him it's from Iruka's parents' homeland, and asks if this can be a secret between the two of them. Surprisingly, for such a loudmouth kid, Naruto never breathes a word of it to anyone else.

Late that night, when Naruto is asleep on his improvised bed, Iruka thinks of how the boy drank down the story of Nausicaa with shining eyes. There is something missing in Konoha, he thinks, something the people of the Valley know, or knew once, that Konoha doesn't have yet and perhaps has never had.

And how did Naruto, the orphan, the troublemaker, whom no-one but the Sandaime gave a damn about before Iruka, seem to know and recognise and cling onto that something when he heard it in the tale?

Iruka is vehemently opposed to war, and he takes it seriously.

For this he is despised as 'soft' by some in the higher levels of the Village, although the Sandaime, who knows Iruka rather better, respects him for it. Iruka has never experienced war: he was born during the Third Shinobi War, but by the time he was even in the Academy it was all but over. He doesn't understand war, those who disagree with him like to say.

This may be true, but what Iruka's detractors don't know is that Iruka is – despite being, always, a child of Konoha – the product of a culture that remembers a war one thousand years ago, and has lived with the repercussions of it ever since. His parents didn't need their breath masks anymore when they found themselves stranded on the Hidden Continent, but they kept them anyway. Iruka has seen them.

When you know that a war can so damage the earth that the soil and the water and the air are still poisoned a thousand years later, that it can doom people to living in tiny settlements in an aptly-named Sea of Decay, that one thousand years after the end of the war people are aging quickly and dying young with hands like stone because of what was done…

When you know this, any cause seems petty.

Iruka fails Naruto for one reason, and one reason only: he believes Naruto isn't ready. It's not just the skills but the attitude that he lacks. Iruka is fully prepared to work on it with him for the whole of the next year, he believes that Naruto is finding his way onto the right track, that soon enough Naruto's potential will be unlocked and he'll blast his way triumphantly through his next genin exam – but not now.

Then Mizuki – Mizuki, that bastard – decides to play his cruel trick, and Iruka is running – he doesn't even have his sword – trying to draw him away from Naruto, desperately – He dodges, weaves in and out of the trees, disguises himself. Fire destroys. There is no attack here. Illusion, misdirection, evasion, the tactics of the water and the wind.

He is forced to stop, though: he can't lead Mizuki out of the village. Instead he reveals his deception and goads Mizuki into divulging his true allegiance. The consequences of what Mizuki discloses take rapid shape in his mind, a complex spider's web that keeps him thinking for a second too long as the shuriken ploughs sharply into his back.

He manages to twist so that it misses the spine, and then Naruto appears… and proceeds, in a thousand incarnations, to beat the shit out of Mizuki.

He has learned Kage Bunshin in an hour, maybe two. No-one will let him remain at the Academy now, no matter how much more grounding he needs in the basics: those who wanted him dead will see this as another reason to push him onto a team where he can be more closely supervised, those who wanted him to become a weapon will see this as proof they were right and reason enough to accelerate his training.

Still, Iruka thinks, looking at the victorious Naruto, that maybe, despite all the obstacles that will be thrown his way (teachers who can't teach, teammates who won't work with him, a system set to destroy him)… maybe, with this kind of creativity, this determination, he'll make it out alive and intact.

Like Nausicaa, if he can't find a way, he'll make one.

There is a saying: those who can't do, teach.

Iruka doesn't think of it that way. A shinobi's work is to protect. He likes to think of teaching as protecting everyone. By training new shinobi, he protects the civilians; by training them himself, making sure their minds are strong and healthy, that they are truly, thoroughly ready, he protects the shinobi. This is the work of a teacher.

Here is Iruka's saying: those who protect civilians are shinobi. Those who protect both are teachers. Those who do not understand this – cannot teach.

When Oto invades Konoha during the chuunin exams, Iruka is in charge of evacuating and protecting a class from the Academy, shepherding them to safety. He reassures them as he herds them along, at the same time keeping a lookout for enemies.

As it turns out, this was a good idea. There are several clan children in that class that Orochimaru would be delighted to get his hands on. Iruka gets the children to a safe place, under a low ledge that no-one taller than them could get beneath, and draws his sword.

What happened that day is known only to a few people, but the children of that class come away with a new belief that they unanimously agree on and would fight to the death (figuratively) to uphold:

Iruka-sensei is the coolest.

When Naruto comes bounding up to tell Iruka that his elemental affinity is wind, Iruka lets out a laugh of delight before he takes him out for ramen.

Iruka is not a superstitious man, but this can only be a good omen.