Okay I’m just going to make it clear from the get-go that I’m going to be disregarding a lot of game canon in this post, particularly the stuff from Black and White 2. I didn’t much like the expansion they did on N in those games and take a difference stance on his and Ghetsis’ relationship. So. Here we go.
N is Ghetsis’ biological son (because how could he not be, let’s be honest? They look the same) and was born to a long bloodline of vaguely royal ancestry. The Plasma cult was established long before N was born, and his future as its king predetermined before he was even conceived. However, despite his place in a grander scheme, Ghetsis genuinely loved his son at first. He told him, constantly, that he was destined for greatness. He wanted him to succeed, to stand by his side and help him turn Plasma’s dreams into a reality.
It was a difficult birth. The Plasma cult was ancient and weighed down by tradition, so N’s mother was denied any form of pain relief, let alone the assistance of a medical professional. She made it through, but only just, and her general health grew worse in the following months as a consequence. She had always been a frail woman, but she was dedicated to her husband and his practices, and so proud to have borne him a son.
Initially, N went by the name Neyiri. He was a curious child, bright and social, revered and adored by all in Plasma. Even at a young age, he was encouraged to play in the gardens surrounding the castle, which were populated by both wild and abused pokémon, brought there to escape the ruling of humans. N would wander the vast, woody forests and plains for hours at a time - accompanied, at first, by Concordia or Anthea or some other dedicated nursemaid. As time wore on, however, they felt able to trust the pokémon in the gardens, who treated N as one of them, to keep him safe on his expeditions. They kept as watchful an eye on him as any human, and certainly knew the dangers of the grounds better.
And that was how N, barely older than three years old, found himself padding through the woods unaccompanied, with only wild Pokémon to supervise him. He had long since formed a close friendship with a zorua, which was barely older than him and pined whenever he went away, and it liked to follow him around, unwaveringly, as he explored the gardens. There were others, of course - a darmanitan, a liepard, an unfezant - that looked in on him and checked that he had come to no harm, but the zorua was his true companion. It never left his side.
And it was this zorua that saw N die.
It happened suddenly, one lazy afternoon in July, the sun still high in the sky. N, about three and a half at the time, discovered a gentle stream in the middle of the woods, and set about to shedding his shoes and playing in it. The zorua joined him, darting in and out of the current, trying to jump across the water without falling in. It was only when N tried to copy it, leaping back and forth over the stream, calling for the zorua to watch, that he slipped on the grass and hit his head.
The zorua froze. It barked at the boy, patted him, tried to get him to wake. When he wouldn’t, the zorua panicked, and did the only thing it could think of.
It cast an illusion over itself, and turned into the boy that it had just watched die.
It took hours for the zorua-N to find its way back to the castle, so long that Concordia and Anthea were ready to venture out and search for him. He was eventually discovered in one of the castle halls, standing limply, blood all over him and completely silent.
The place fell into panic. They steered N aside, scooped him up, asked and asked and asked him how he had hurt himself, who had hurt him, where he had been hurt, but he wouldn’t - couldn’t, as a young zorua - reply. It wasn’t until they washed the blood away entirely that they noticed he was unscathed.
He wasn’t like the real N. He couldn’t be. A young zorua has no idea how to be human. He couldn’t speak, turned his nose up at human food, lost all of his curiosity and social flair. It grew so concerning that regulation was broken, and an outsider was invited into the castle. A doctor.
The doctor explained that N was likely to have undergone a trauma. Not a physical one, as the blood hadn’t come from him, but something so psychologically unnerving that his mind had gone into shock. It wasn’t uncommon, he explained, to stop speaking in response to distress, nor to abandon your usual habits and seem completely disconnected from the real world. But until N started to process what he had experienced, or regain his speech to tell them about it, there wasn’t much they could do.
Concordia and Anthea accepted this explanation. So did N’s mother. But Ghetsis couldn’t. The more time passed, the more time he spent around N, the more convinced he became that this child, so silent and distant, was not his real son.
How he knew, it was anyone’s guess. But he couldn’t force himself to believe otherwise, and nor could anybody else. He grew resentful to N, accusing, would no longer call him Neyiri - not that name, not his son’s name. His wife pleaded with him, but she was growing weaker with the stress, and she knew she wasn’t long for the world. She died less than a year after her son, before making Concordia and Anthea promise to look after N, and to protect him from Ghetsis to the best of their ability.
They did their best, but the death of his wife only made Ghetsis worse. N became a pawn to him, something that he would use but not acknowledge. Even when N started to pick up speech, using broken sentences and mismatched grammar, Ghetsis did not relent. Upon listening to the boy’s stilted grammar, strange vocabulary, odd speech tempo, his suspicions were only cemented further in his mind - his son had never talked like that, never used those words.
So N was neglected, confined, controlled. Manipulated into believing exactly what Ghetsis needed him to believe, and tricked into thinking that he was the true leader of Plasma. Ghetsis couldn’t let this changeling take his son’s place as king, but he could use him to gain the power for himself. N was still the beautiful, innocent waif that people liked and listened to, the perfect public figurehead. If he wanted to pretend to be Neyiri, Ghetsis would pretend to make him team Plasma’s king, and take the power for himself once N’s work was done. In his mind, it was a fair exchange. It was revenge.
Somewhere along the line, N would have forgotten that he was a zorua at all, and convinced himself that he really was the boy he once befriended. That is why reshiram would present itself to him. To help him uncover the truth about what he was, and show him that the boundaries between humanity and pokémon are not, truly, black and white. He is the proof of that.