They played several rounds with little conversation. Button Mash was clearly better, though it was not entirely a landslide as the prince managed to win once to his muted grunt of annoyance.
Button suddenly hopped to his hooves after a round and casually walked over, clicking the system off. "Well, that was fun!" He never turned to face the prince, instead veering towards bed. "I should get some sleep before mom comes in and gets mad."
The prince felt himself deflating a little. He had been forgotten mid-game at some point. Did Button Mash think he was playing against the AI, or perhaps just really wasn't thinking about how the other pony moved. He raised a hoof to wave gently to the settling foal.
His movement to the window did not alert Button and a little smile returned to him. At least he had stopped being innately 'wrong' simply by being there. It was the tiniest victory, and one he accepted. He pulled himself up onto and subsequently through the window without much of a pause, flopping about as gracelessly as Button had coming the other way.
"Oh yeah." Button appeared a moment later, pulling down the window closed. He vanished a moment later, likely back towards bed.
He was outside, in the dark. Ponyville did not become completely dark after the sun set. Light spilled from some homes, dispelling pitch darkness. The moon was also out, shining brightly with its starry cohorts. He moved by their guidance, trying to make his way back to the hotel he had chosen to inhabit.
"Hey!" He stepped back a half-step as Pinkie sprang from a bush just in front of him. "There you are. I've been looking all over for you. For a moment I was scared. 'Oh no! Now I can't see him either!'" She clopped both forehooves to a cheek as she gasped dramatically. "That would be just awful, but phew, nope, there you are."
The prince shook his head as he recovered. "Still here, and you can still see me." He glanced back towards Button's house. "Oh yeah, I returned his game."
"Already?" Pinkie tilted her head at that. "I thought you'd play it a little longer."
"It was fun, promise. It was kinda by accident." He shrugged softly. "Nothing for it now."
"I could go get it again," she offered as she reached a hoof behind her back. She rose up onto her hind legs as she did so. "By the way, I talked to Twilight again."
"And she had no idea who I was," he completed the thought with a soft huff.
"That's not true. She remembered everything we, I mean her and me, everything we talked about. She even agreed to try to help!"
The prince cocked a brow at Pinkie. "I'm not going to be put in an cage to be forgotten about. That sounds like a sad way to go."
"What? No! Blah, no." Pinkie shooed the thoughts away with wild motions of her hooves. "She just said to bring her some 'samples'. You know, a little fur, some mane, that kinda thing."
"Oh, sure." He shrugged softly. "So far as I know, I just grow new fur whenever I become another pony, so go ahead."
"Thank you!" She bounced towards him, scissors wielded in her hair suddenly. "Just a little snip snip!" Each time she said snip, the scissors closed, chopping off a bit of his mane, then getting some fur off of his shoulder, each falling into a different little baggie. "Spit please." She held up a new little dish as the other baggies were put away quickly.
"What? Really?" He peered at the empty little dish. "Whatever..." He soon produced the desired fluid. "Do you think she can do much with that?"
Pinkie topped the dish and had it put away. "Dunno, but worth a try! It was her idea and all. Now, uh, this next part needs you to trust me." Out came the hypodermic needle, wielded between her hooves. "Twilight said it'd pinch a little, but it'll be over in a moment."
The prince cringed, backing away quickly. "Woah! I don't like needles!"
"Is that what this is?" Pinkie peered at it suspiciously. "How can you make clothes with one of these?"
He applied a hoof to his face. "Not that kind of needle, and that makes me even less want to let you poke me with it."
"I'll be super careful, promise." She took a step close, balancing on two legs quite well. "Don't you want Twilight to fix this?"
"She probably won't," he sighed out in defeat. "I appreciate you wanting to help though."
"So let me help. Just a moment." She tossed her head towards his back end. "She said right in your cutie mark was a good spot."
The prince glanced away and back at Pinkie wielding a needle. That was not what he had imagined he would encounter that night. "Do you even know how to use that thing?"
"She showed me." She took another step closer. "And I paid attention, promise. I don't want to hurt a friend. That would be just awful."
A ghost of a smile touched his lips. It was... kind of nice being called someone's friend. "Will... it hurt?" The question felt lame even coming from his lips. "Nevermind, of course it'll hurt. You don't get jabbed without it hurting." He put a hoof to his face and closed his eyes. "Just make it fast."
"You got it." she took the last step and reached out an empty hoof. She felt along the smudge that was his cutie mark. "Here." She tapped a part. "She said to look for where I can feel your heart going thump-a-thump. Now..." She set the needle into her hair to be held as she pulled out a cloth and wiped the prince down with something that smelled of alcohol. "No infections for nice ponies."
Being sterilized relaxed him a little. Maybe Pinkie did know what she was doing? Suddenly he was bit, or jabbed. He felt the needle poking into him and squeaked. "I thought you'd warn me!"
"But then you'd be all tense and stuff. This way I'm already done." Pinkie gently withdrew the needle full of his life essence. "Now we bandage..." She applied a big wad of cotton to the part of his leg she poked and got some medical tape going the full length around the leg. "Ta da!"
The prince looked over his shoulder at the new bandage. The pain was already ebbing away bit by bit. "That... wasn't too bad... So, are we done then?"
Something plastic was shoved up against him. He blinked before realizing it was a potty. "W-what?"
"Do your business." She shrugged softly. "Last thing, promise."
His cheeks warmed dangerously. "Not in front of you!"
Pinkie looked around a moment. "Borrow a pony's outhouse if you have to." She pointed to one of the few in Ponyville. Most of the residents enjoyed indoor facilities. "Just, you know, do... everything, then come back."
He shook his head quickly. "May I remind that I can't use my horn without being disguised as a unicorn? My hooves aren't sticky, and my wings aren't that good either. You want me to hold this in my mouth? No!" He stomped a hoof down. "Give me like a cup or something and I can... do half of it and leave it for you. That's my best offer."
"Why not just do all of it and leave it for me?" Pinkie bounced in place. "That's a great idea."
He emitted a noise between a grunt and a sigh. "If I don't have to kiss something that... fine." He looked around for that outhouse. "Put it in there, come out, let me have my turn, then it's all yours."
"You're really sensitive about what your mouth touches." She shrugged softly. "Seeing as you're basically an earth pony when you're not being something else, you should work on that." She trotted towards the outhouse, slipping inside a moment to emerge without the potty. "All ready!"
The prince approached more sedately. "What you put your mouth on, you taste. You also smell."
"I do not!" hotly defended Pinkie, scrambling back a step.
The prince blinked, getting it a moment later. "I mean, whatever you hold that close to your face, you're going to get a good whiff of."
"Oh, well, that's true." She shrugged softly. "Go on." She pointed to the outhouse. "I'll wait out here."
"Good, you... do that." He did not require assistance to perform what was ahead. He vanished into the outhouse, emerging a short time later. "All yours." He did not pause in his scurrying flee. That was enough Pinkie for one evening as far as he was concerned.
Pinkie clopped her hooves excitedly. "Got it all in one evening. I thought I'd need at least a full day." She went in to retrieve the last of the samples. "Twilight'll be so proud of me!"
Twilight accepted the box Pinkie had brought her. On one side 'Prince of Errors' was written in a foalish drawing. "This is... everything?" As she floated it past herself, her nose wrinkled. "Oh, yes, everything... No problems with the blood sample?"
Pinkie shook her head quickly. "I did it exactly like you said to do it. It wasn't that hard once he relaxed."
Twilight pondered how she had managed to calm this theoretical prince. She had her doubts, but the evidence was in front of her, so... "I'll examine these and see what I can find. Of course, there's no assurance I'll see anything obviously abnormal, but this is a fine start."
"I'll leave you to it." Pinkie saluted sharply. "I'm no good at science stuff."
"Thank you." Twilight nodded as she turned away. "I'll tell you the moment I know something worth reporting."
Spike shrugged softly as Twilight wandered off. "So, really, this isn't some crazy prank of yours? I would think I'd remember talking to somebody."
"You did!" Pinkie huffed through her nostrils, flaring them in the motion... "I was there, I saw it. Only the prince and me remember it though. Oooo, it's so frustrating!"
"I can imagine," agreed Spike without sounding convinced. "You know, it's perfectly normal for ponies to have imaginary friends, though they usually have them a bit... younger."
"Spike!" Pinkie frowned at him. "That wasn't even nice."
He held up his hands. "Hey hey, just saying. If you're embarrassed, don't be. This'd hardly be the strangest thing you've ever done."
In another room, Twilight set down the box gently. "If that fur is pink, I swear..." She pulled open the flaps of the box with her magic to reveal the samples. The fur and hair were in the baggies she had supplied. Inside them, pony hair and fur! Also, pink.
Twilight's eyelids closed to halfway, glaring at them. "She... didn't...." Had Pinkie just taken samples from herself to validate her mysterious pony friend nopony else could see or interact with?
"Maybe I'm jumping to conclusions. She's not the only pony in the world with pink fur or a pink mane." She let out a slow breath. "Approach this methodically. Let's have a look." She willed the baggy with the mane clippings up into the air and pulled it over to her microscope. She slipped it into the viewing portion and took a peek.
Each hair was curly and vibrant. It was difficult to imagine they had come from any pony that was not Pinkie. "They have a few dead ends," she muttered in observations. Aside from that, the hair looked perfectly normal. She swapped the mane for the fur clipping. "Smooth, healthy, just the right amount of gloss... How does she manage that on a diet of 80% sugar, I remain baffled."
She could conduct more invasive chemical tests, but it was feeling like a waste of her time. "Let's skip to the most telling bit of evidence." She plucked up the full needle. "Blood can't lie. If this came from Pinkie..."