It didn't take Raph very long to decide that he was not going to spend his time on the astral plane standing around a sewer tunnel.
"Where are you going?" Leo demanded, as Raph swung himself back up the ladder.
"Our brother just ditched us," Raph said bitterly, not slowing his climb. "I'm at least gonna go topside and look around."
"You are not going topside," Leo said, climbing just enough rungs to grab at Raph's foot and try to stop him.
"Why the hell not?" Raph kicked at Leo's head, more violently than he probably should have. "There's nobody there, Leo! When are we gonna have another chance to walk around New York while it's totally deserted?"
Leo made that half-sigh, half-growl noise that meant that Raph had out-logicked him and he didn't like it.
"Why is there nobody here?" Raph asked, when they were standing in the middle of the street in front of David's building. There were cars parked along either side of the road, but they were ghostly, as though not fully manifested. Raph and his brothers hadn't seen any cars moving, nor had they encountered a single spirit on their journey, aside from the multiple aspects of Donatello. "Ain't the astral plane supposed to be full of supremely enlightened people?"
"I think we're in a special part of the astral plane," Leo said. "It isn't the way Master Splinter described it to me. He told me it was like a void, where you move around interacting with other people, communicating at the highest levels of spiritual development. That's sort of like where we first arrived. Since then, it's been more like…" He trailed off for a moment. "It's been more like what David imagines the astral plane is. He sees it as being like the earthly world, because that's all he knows."
"Why are the buildings wrong?" asked Raph, who had lost interest in the metaphysical hypothesizing.
"What?" Leo asked.
Raph took his brother's shoulders and pointed him towards the far side of the street, opposite the vet clinic. "The buildings over there look like in the real world. But the ones over there -" He spun Leo through a 180. "- don't. They're wrong."
Leo rotated himself back and forth a couple of times, puzzling over this. "Because it's what David thinks the world looks like," he said at last. "He knows what the buildings across from his look like, because he can see them from the windows. But he's only seen the outside of his own building once, a long time ago. So he just imagined what it looks like."
"Wonder what he thinks downtown looks like," Raph said, beginning to saunter in that direction.
"Don't go too far," Leo warned him, but at least he didn't insist they go back underground.
Exploring the astral version of uptown Manhattan was an exercise in frustration. The clinic turned out to be the only building that had an inside. None of the other doors would open, no matter how hard Raph kicked them.
The street didn't extend too far in either direction before all semblance of reality broke down, to be replaced with vague, foggy placeholders for buildings, cars, stop signs, mailboxes, parking meters, and, weirdly enough, payphones. David seemed to not only not know what was beyond his own front door, but also not care very much.
Raph hoped that wherever Donatello had taken him, they were having fun right now.
And then the two of them were swooping in like Silver Sentry, and Raph had sure never seen Donatello do that before.
"What the -" he said.
"I'll let him tell you," Donnie said, and a feeling of terror - at what, exactly, it was hard to say - began to build in Raph's stomach. He didn't hear what Dave and Don were saying to each other, until Donnie was fixing him with a warm smile and saying goodbye.
"Donnie, wait," Raph said. He didn't know exactly what he needed to say, but he needed to say something - about how sorry he was that such a kind spirit had gotten attached to such a sucky body, about how he should have realized sooner what Donatello was, about how he loved him so much.
But then that thing with the light was happening, and he would never see this Donnie again.
"No!" he screamed, launching himself at the bright figures. "Donnie!" He wasn't moving. Why? He twisted to punch whoever was holding him back. "Donnie, I -"
The next thing he knew, he was on his knees, and so was David, and Donnie was gone, and in his grief Raph almost didn't notice David crumpling to the pavement, panting and shaking.
"Raph!" someone was shouting. "Raph!"
And then Leo punched him in the face, and he snapped back to reality, or something like it.
"He's doing that thing he did when we first met him," Leo said, to help Raph grasp the situation.
"What?" Raph switched his gaze from Leo's face to David's screwed-up spirit body, to verify that this was true. "Why?"
"I don't know!" Leo leaned over David, his hands hovering, unsure what to do to help.
"Where the hell's Mikey?" Raph demanded. "He's supposed to be -" He fumbled for the right words, then settled for jabbing a finger towards David. "- making that not happen!"
"I said I don't know!" Leo shouted, and then they both screamed "Mikey!" just in case anyone could hear them.
It seemed like David was seizing on the pavement forever, and then the spasms subsided, and then, just as mysteriously as the attack came on, it was over.
He opened his eyes and groaned.
"Hey," Leo said softly. He leaned into David's field of view. "What happened?" he asked, because it was just like him to want information from someone as soon as they were conscious, instead of, y'know, asking if they were all right.
David let out a little breath and closed his eyes again.
Leo pulled David up into a sitting position, holding him against his plastron.
"Hey," he said again, and showing that he did have some capacity for compassion after all, he asked, "Are you all right?"
David let out a little string of noises, without moving his lips.
"Fuck," Raph said. "We broke him. Something's wrong with his brain."
"I think he just needs a minute to recover," Leo said gently, and he rubbed David's bare shell, while quietly noting what else had changed about his spirit body since Donatello brought him back.
It took several minutes, but he did recover. And then he was furious.
"I had a blood sugar spike," he said, as if Leo's question had been patiently waiting for him to regain the ability to answer it. "I'm fine. Or as fine as ever." He pushed Leo away and staggered to his pink, two-toed feet, stomping a few paces down the sidewalk and then turning back to glare angrily at his brothers.
"This is all an illusion, isn't it?" he asked. "What's the point of this -" He gestured to his toned, halfway-human guise. "- if back in the real world I'm still a hopelessly sick turtle-man? How are we going to fix that?"
"David -" Leo started.
"Don't talk to me," David snapped. He closed his eyes, pressing a pale, three-fingered hand over them. And then his spirit guise began to shift in the most disturbing ways.
His skin flowed like mud, his snout and shell appearing and disappearing in ragged chunks that made Raph sick to his stomach. He turned green, and then pink again, and then both in splotches, as if someone had thrown paint on him. Clumps of hair sprouted from his scalp in a shifting pattern. One of his hands had five fingers, and the other had three, and he had one ear, and then Raph couldn't look anymore.
"David -" Leo tried again.
"I said leave me alone!" David bellowed, and Raph recognized that as the tone of someone who desperately needed to not be left alone. Indeed, instead of walking away, David kept talking. "I had some kind of a life. I was doing okay. Then you showed up, and handed me the key to a cure, and told me not to use it. What am I supposed to do? I don't want to be here anymore, Leo! I want the surgery!"
Raph's heart plummeted. Donatello - the real Donatello - was gone, and David still rejected being a Turtle?
Maybe that meant that Donatello would come back. Maybe in a second he'd come flying out of David's horrifying body, and -
The thought felt so right, and yet Raph was sick again at how selfish it was.
Raph looked up, and saw Leo hugging the monster that David had turned into.
"It's okay," Leo was saying. "It's okay. You can do whatever you want."
"I want to go home," David said into Leo's shoulder.
"We just have to wait for the medicine to wear off," Leo said. He pulled back just a little, his hand sliding down to David's wrist. "Let's sit down and talk about our journey."
David hesitated, but he had nowhere else to go and nothing else to do. In a moment, he sat down with Leo, right in the middle of the street, and Raph joined them, staring at David in disgusted fascination. David ignored him.
"Tell us what you've learned from the Donatellos," Leo said.
David didn't seem to want to talk about it, but after picking at his mottled skin for a while, he relented. "The first Donatello showed me that I am a turtle," he said. "At least on some level. And there are some things that turtles can do that… are pretty cool," he admitted grudgingly. "The second Donatello taught me that I should trust my instincts more. Logic and reason have their place, but sometimes I just have to go with my gut."
Leo nodded, encouraging David to go on.
"The third and fourth Donatellos showed me that I don't have to be a sickly weakling," he said, and then added bitterly, "which, as we just saw, is not entirely true. But I can do better than I'm doing now, without radical interventions."
"Tell me more about the fourth Donatello," Leo prompted. "I didn't understand what he was saying to you."
David sighed, and fiddled with his mismatched feet. "He said that I'm overmedicating. I'm on the wrong side of the therapeutic dose, and the side effects are outweighing the benefits. He suggested I try managing my various issues with a healthier lifestyle, rather than with pharmaceuticals."
"Um…" Leo glanced at Raph, but Raph just shrugged, equally in the dark.
"The therapeutic dose," David said, and outlined something like a small hill in the air. "Or the effective dose. The amount of medicine you need to take to feel better. Take less than that, and it doesn't do anything. Take more, and it does things you don't want it to do - things that hurt you."
"And the second part?" Leo asked cautiously.
"He said I should take less medicine and get more exercise," David explained. "Eat better food. Things like that. He - He suggested I try being a Turtle." David rubbed his arm, obviously uncomfortable with the idea. "Maybe you guys can show me how."
"We would be honored," Leo said. After a pause, he asked, "And the fifth Donatello?"
David grimaced. "Told me I should explain things that way, instead of telling you you're idiots. How'm I doing?"
"Not bad for a beginner," Leo said, pressing David's shoulder, and Raph had to respect his tact. "What did he tell you at the end?"
"He said he was leaving us a trail to his next incarnation," David said. "But I don't know what it looks like."
"You didn't have a vision?" Leo asked, and David shook his head. "Do you want to continue your journey?"
David looked up at the sky, which was a strange, uniform blue. "We're trapped here until the medicine wears off?"
"I think so," Leo said.
"Then we may as well look around." David climbed to his feet, more steadily than he had earlier. His spirit body was still hopelessly caught between human and Turtle, but it didn't seem to bother him. "What else do I have to lose?"
They searched the street, and Raph found it first - a chalk marking on the manhole cover Leo had fastidiously replaced when they came up from the sewers.
"Check it out," he said, waving his brothers over. "Sewer sign."
"What is sewer sign?" David asked.
"Y'know hobo sign?" Raph said. "It's like that."
He took pleasure in the fact that David just stared at him, no more enlightened than he had been a moment ago.
"It's a way of leaving coded messages for each other," Leo explained. He leaned over the manhole cover. "It says go down."
"But we've already been that way," Raph complained.
"Then we'll go that way again," Leo said. He slid the cover aside and jumped down, and Raph didn't have any real choice but to follow.
Just as Donatello had said, there was a trail of signs. Many of them were directional - left, right, and continue straight - but some were encouraging, or as close as it was possible to get in the limited vocabulary of their symbol language.
"Safe here," Leo translated, when they reached one sign, and "Interesting place," Raph interpreted, when they found another.
"Why is this interesting?" asked David, who didn't seem able to distinguish between one stretch of sewer tunnel and another.
"We used to play here," Raph said.
"Here?" David cautiously shuffled back against the wall. "But it's a puddle of sewer water."
"Yeah," Raph said fondly. "Good times."
"Do you know where we're going?" David asked.
"Think so," Raph said, but he wouldn't give away his guess.
He turned out to be right. "Stop," he said, tracing the last chalk sign with a finger.
"Why stop?" David asked. "We're in an empty tunnel."
"No, we aren't," Leo said, and he stuck his finger in an almost-invisible crack in the brickwork, and pulled open a hidden door. "Welcome home."
The space inside was obviously no part of David's memory or imagination. It was perfect, a time capsule the size of an entire room. Every piece of rundown furniture was there, along with every mismatched decorative item they had hung on the walls, having no idea of its cultural significance, but wanting to surround themselves with the things that humans liked. There were the curtained-off "bedrooms," and Master Splinter's alcove, and the talking box they had spent so many hours in front of.
Raph rubbed the tears from his eyes, and when Leo looked at him questioningly, he mumbled something about the dust that hung thick in the air.
"What is this place?" David asked.
"This is where we grew up," Leo said, and he moved towards the fire pit and the water tank with sure steps. He had spent most of his life here, had been trained to navigate it in the dark, and he hadn't forgotten.
"Where is Donatello?" David asked.
Leo pressed a finger to his beak, and inclined his head towards the other wing of the L-shaped space.
Raph got it immediately - the soft footsteps and little expellations of breath of someone practicing ninjutsu. Donatello was still here, in this spirit world. He had come home.
"Go to him," Leo whispered, and David edged forward.
Raph followed, unable to not look. As he and David came around the corner, Donatello didn't stop his practice. He was facing away from them, and his spirit form was about eight years old, not yet skilled at detecting a quiet approach.
He was on the mats, training with a jo, and he was frustrated. Raph remembered this.
"Raphie, I'm no good at this!"
"Yes you are. You just gotta keep trying."
"Show me how…?"
"Hey," David said softly.
Donatello startled and spun to face them, brandishing his small weapon as best he knew how. "Leave me alone!" he shouted. "I don't want to see you no more!"
David went to him anyway, kneeling beside his much shorter spirit double. Donatello, at least, didn't seem repulsed by the form David had taken on. "What are you doing?"
"Practicing ninjutsu," Donatello mumbled.
"Will you show me?" David asked.
"No!" Donatello shouted. He moved to strike David, then pulled the attack, since to complete it might count as showing him ninjutsu. "I'm not any good! You'll make fun of me!"
"You're better than I am," David said. "I don't know any ninjutsu at all."
Donatello watched him suspiciously. "You won't laugh?"
"I should be asking you that," David said. He stood up, taking his best approximation of a ready stance. "Come on. Teach me how."
Sure enough, Donatello was already struggling to repress a smile at David's sloppy pose. "You gotta stand like this," he said, setting the jo aside and adopting a fierce stance. David copied him, more or less. "Then you gotta do this." He stepped forward into age uke, an upward block. "And then this! Choku zuki!"
"Cho-gu ski!" David shouted, imitating Donatello's punch.
Both maintained fearsome expressions at their imaginary opponents for about two seconds, and then both burst out laughing.
"I'm laughing at myself," David said quickly.
"I'm laughing at you," Donatello said.
"Well," David said, dropping his arm and coming back to a neutral stance, "at least you're honest." He moved forward to stand over his younger self. "We're not very good ninjas, are we?" he asked.
"No," said Donatello. "But we're really smart."
David sat again, cross-legged, and his counterpart did likewise. "And we'll never really be normal, will we?" he asked quietly.
"No," said Donatello. "But we can help people."
"How?" David asked.
"Be nice," Donatello said. "Make things. Have honor."
David held out a hand, tentatively. "Do you think you can help me, right now?"
Donatello nodded, but apprehensively.
David laid his right hand - green and three-fingered - on Donatello's bare scalp. "Does it hurt you, when I do this?"
"Yeah," Donatello said. He curled his fingers around the jo, lying on the mats next to him, and brought it across his lap in a protective gesture. "I'm scared."
"Don't be scared," David said.
"Guys?" Leo called, from around the corner. "I think we're running out of time."
"Thank you for teaching me," David said.
"Dōitashimashite," Donatello said, in his child's voice, and then the light spread down from David's palm, enveloping Donatello before lifting up and washing back across David's malformed body.
"Guys," Leo said. "We have to go."
Instead of fading, the glow spread, and their entire home vanished into the light.