They say that it stays still and quiet because it is seeing both the past and future at the same time.
Pokémon Gold Pokédex Entry for Xatu
Despite what the old hornless Nidorino had said, Aurinko was still a little edgy around the Natu. There was always at least one staring at her, sometimes all four of them at once. The other Nidos in the enclosure tried to tell her they were always staring at something for what they could see as no apparent reason, but Aurinko wasn’t convinced. She’d been stared at and commented on all her life, except when she was stuck in the burrow where she was ignored as much as possible. She could tell they were staring at her because of her strange colouring.
The Natu were silent creatures, never saying a word, not to each other and not to the other Pokémon in the zoo. This made them all the creepier. Nidos are very social animals, and the lack of communication between the green psychic ground birds was foreign to them, even to the members of the ‘mob’ who had been in the zoo for as long as if not longer than the Natu had.
The word of the coming Xatu had spread throughout the zoo. The Nidos had heard it from the Dragonair, who were told by the neighbouring Stantler that the Zubat had overheard the zookeepers talking about maybe just possibly considering the idea of thinking about getting a Xatu. It was all very intricate stuff. The zoo Pokémon had a system—if you know anything, tell everything.
Aurinko had begun to grow slightly frightened of the prospect of her new neighbour. The Natu alone managed to set her on edge with their constantly staring red eyes, what would their evolved form be like? She asked Talvi what she knew about Xatu.
“They’re the evolved form of Natu.”
“I’m not much older than you are, ‘Rinko, haven’t seen much outside the zoo. Ask Akan, he’s been around.”
Failing a response from her most trusted source of information, Aurinko asked her question to the hornless head male, Akan.
“They’re the evolved form of Natu.”
“And?” Aurinko didn’t like where this was going.
“They’re very mysterious creatures. I don’t know much, but I’ve heard they can see into the past and into the future.”
Aurinko raised an eyebrow.
“That’s only what I’ve heard. I don’t believe it myself, but I guess we’ll find out soon, eh?”
“Yeah, whatever you reckon.” Seeing into the past couldn’t be that hard, Aurinko thought, couldn’t be any different from remembering. Seeing into the future? Yeah right.
It wasn’t too long until a medium-sized truck with the zoo’s logo painted on the side drove noisily through the zoo. Naturally, every Pokémon within viewing distance had their eyes trained on it. They all knew this would be the Xatu.
The Natu were nowhere to be seen, they had been locked up earlier in a cage so they couldn’t escape when the Xatu was put in with them. The truck reached the cage and reversed, beeping constantly, in through the opened gate.
The zoo hadn’t been opened as yet, and the visitors were yet to arrive, so the surrounding Pokémon all had a good view. Akan was describing the scene in great detail to give Mekura, the blind Nidorina, the best mental picture she could receive. Every other Pokémon was silent but for those relaying it on to the enclosures behind who couldn’t see the action.
The gate to the Natu cage was closed shut, and the three men dressed in the khaki green of the Safari Zone and Fuchsia City Zoo returned to the truck. Two swung its doors open while the other reached into the back to bring the mysterious psychic bird out.
The bird’s head looked much like the body of a Natu, only its crimson feather and sharp beak were longer than those of the bird it had evolved from. Its snowy wings, tipped with blood drops and charcoal, were folded neatly over its olive green chest. Its two bright red feet clutched the zookeeper’s khaki sleeve and the bird remained motionless.
The zookeeper carried it carefully to the tree in the corner of the cage and set it on a branch, where he left it and returned to the truck. The truck made its way out of the cage and the zookeepers let the Natu back in. The four Natu scuttled over to the Xatu and lined up in front of it, staring up at it in what looked like awe.
The Xatu was absolutely silent, not even the sharp ears of the Nidos could pick up any noise from it. It stood on the branch still as the hot, muggy air that hung around the zoo. Slowly, with mechanical smoothness, its head began to turn, its intense eyes meeting all of those it passed. Anyone talking fell silent, and as the Xatu’s gaze passed over them, they took a step back. Even Mekura could feel a shiver run up her spine as its cold, all-knowing eyes met her own, unseeing ones.
It kept Aurinko’s eyes held with its own for much longer than any other Pokémon, and Aurinko knew it was because of her colour. She gulped, wondering why it wasn’t moving on. She placed her feet in what she hoped was a battle stance and glared hard at the Xatu, but it didn’t even blink, it just kept staring at her, and no matter how hard she tried, Aurinko just couldn’t pull herself away from it.
She felt as though its eyes were spears, piercing into her mind, digging up every memory she had, every horrible, painful memory. Aurinko could feel new pain blossoming in her forehead, leg and side, and it was all she could do to keep from crying out.
Talvi could see the pain she was in and pushed her over, forcing the Xatu’s painful stare to move on.
“Aurinko!” she asked, her voice trembling, “Are you alright?”
Aurinko was panting heavily, but managed to nod before collapsing to the dusty earth from exhaustion.
“What did it do to her?” Talvi whispered over the sleeping albino.
Akan shook his head, just as bewildered as she was. “I don’t know, but I think that creature is one we have to beware of.”