A perimeter alert dinged softly.
In another life, it would have been an earsplitting alarm, blaring across the cavernous space to warn everyone that someone or something had breached their first line of defense.
It was strange that he knew this.
Technically, he'd only been here a few minutes. He had arrived abruptly, reeling from the aftereffects of having had part of his soul drained out of him. He remembered the other life he had just come from, and the one before that, and the one before that.
But he also remembered a life he'd never had, a life that wasn't his - the life just on the other side of a tenuous but strengthening connection.
And now, suddenly, he remembered a life he could have had, and everything about this space was as familiar to him as if he had always been here. As if his family had always been here. He knew them from spending his whole life watching, trapped behind an impenetrable veil.
But they weren't here. They never had been. The bedrooms upstairs were empty, save for one, and the perimeter alarm was just for him, because no matter how loud he made it, they would never hear.
He slid the mouse to the side, with the ease of long practice that had never happened, and opened a window on the monitor. In a couple of clicks he'd disabled the alarm and turned on an audio feed.
"I can't believe I got such a nerd for a brother."
"I can't believe I have such a technophobe for a mom. The things I could have done."
"What even was all of that? … No, don't tell me. I don't want to know. Where is Donatello? He said he'd be here."
"No, he said we should wait for him here."
"Well, he better hurry up. I ain't real good at waiting."
He shut down the program and turned off the monitor. He stood up, stretching - involuntary re-embodying was painful - and slid his bo home behind his shell.
He'd never been here before - with the way the astral plane worked, it probably hadn't existed until just a moment ago - but as he headed out through the heavily-reinforced door, he knew exactly where to go. It took him only a few minutes to navigate the dark and twisting passages of the sewers, and find his brothers.
He saw Raph and Leo tense at his approach, reaching halfway towards their weapons, on guard in case he was not who they were waiting for. As he came into the glow of the fluorescent lights, they relaxed - and then their expressions turned to shock as they realized what he was.
"Damn," Raph said hoarsely, not quite mustering the entirety of his voice. "Bro…"
It was hard to say who moved first, but they fell into each other's arms, and then he was hugging Leo, and everything would have been exactly right if only Mikey could have been there too.
"Donnie," Raph said into his shoulder. "This is who you shoulda been."
"I'm sorry," Donatello said. "I couldn't be."
He waited until Raph pulled back, in his own time.
"Where do you wanna go?" Raph said. "Anyplace. I don't care."
"Actually," Donatello said, "do you mind if I talk to him in private for a little bit? Thanks." And without waiting for an answer, he took David's arm and pulled him down the tunnel.
"Hold on a second," David said, as he stumbled along behind Donatello, glancing back at their brothers. "I don't know if I should go off alone with you. You already tried to kill me once today."
"Don't worry," Donatello said. "I don't do that anymore." He tugged David forward, then pushed him along by his incongruous shell. "We need to talk. But first, I need to show you some things."
"Where are we?" David asked.
"Remember when Leo and Raph told you they live in the sewers?" Donatello said.
"Yes," David said. His brow furrowed. "How do you know? You weren't there."
"I have your memories," Donatello said. "Anyway, we're near where they live. Or the astral equivalent of it."
David dug in the heels of his sneakers against the filthy concrete. "This is where they live?"
"David." Donatello came to a stop, not pressuring his spirit twin to move on. "What I'm going to show you is what your life could have been, if you had grown up with them. You won't like all of it. You would have not liked all of it, in a different way, if it had been your real life. It's up to you whether you want any of it."
David looked at his feet, then looked up again. "Okay."
"First of all," Donatello said, "you would have looked like this."
He let David take a good look at him. He was a mutant Turtle, through and through, like his brothers - in good health, despite his difficult circumstances, and leanly muscled all over. He stood confidently, knowing his body would have put him at risk in the earthly realm, but trusting it to obey his every command.
David tentatively touched his elbow pad. "Tell me that isn't leather."
"Sorry," Donatello said. "Good synthetic protective gear is hard to come by."
David's eyes moved to the staff behind Donatello's shoulder. "What is that?"
"It's called a bo," Donatello replied. "You've never loved being a ninja, but this is a subtle and versatile weapon you feel good about mastering."
"What's up with the masks?" David asked bluntly.
"Kind of hard to explain," Donatello said. "Ask Leo about Japanese history and culture. But make him ration the lectures."
"I still don't understand why my alter ego doesn't wear clothes," David said.
"He didn't have an Aunt Terri to custom-make everything for him," Donatello said.
David fiddled with the seams of his plastron. "You know about Aunt Terri too?"
"And your mom," Donatello said gently.
David thought about this for a moment. "My mom? Not yours?"
"She didn't raise me," Donatello said. "I've never met her. But I know her through you. She's a special person."
"Yeah," David said quietly. "She is." He stared at nothing for a long minute. "Where are we going?"
"This way," Donatello said, and he led David up a ladder into a shining New York night.
It took only minimal convincing to get David to climb a fire escape. In their previous meetings he had accepted his strength and his health, and - at least in his spirit guise - he was more than capable of handling ladders and staircases. He gathered his courage and pulled himself up onto the roof.
And then he balked at the idea of jumping.
"You want me to do what?" he said.
"Jump to the next roof," Donatello said again, pointing to the wide, flat roof that lay just on the other side of a narrow alley from them.
"You're joking," David said.
"It's the only way to travel," Donatello said, and in an effortless bound he cleared the gap and turned around to beckon David to join him.
To his credit, David did it. The jump wasn't graceful, but it was more than powerful enough to carry him to his destination.
"Okay," David said, reaching for Donatello's shoulder. "I definitely want this."
"Wait," Donatello said, as a line of light began to leap between them. "Don't take it yet. I still need it."
David pulled his hand back, the light retracting into his palm like the crack of a whip. "Won't you still be able to use it through me?"
"I don't know," Donatello said. "I've been here my whole life and I still don't understand the metaphysics." He turned towards the far side of the roof. "Let's not take our chances. Follow me."
And they were off. Even without having re-absorbed the skill, David quickly picked up the rhythm of running, pushing off, landing, running again. He didn't attempt any flips - which was probably wise - but he watched closely as Donatello showed off some of the abilities he would have had if he'd grown up as a ninja.
It seemed to take no time at all before Donatello pulled them to a halt on the roof of a low - by Manhattan standards - office complex, just across from the Empire State Building.
"Let's go there," Donatello said, pointing to the iconic spire.
David looked at their target, and looked at the six-lane street far below. "That is categorically impossible," he said.
"Not for me," Donatello replied. "Come on." He took David's hand, and without exactly pushing off, he simply lifted into the air, towing his spirit double behind him.
They skimmed across the street, and then they were shooting up the side of the tower, the wind rushing past their faces, their plastrons almost scraping the art deco flourishes between each row of glass. In barely a minute they were up over the pinnacle of the building, and then they were setting down lightly on the highmost deck.
Donatello didn't let go of his other self's hand until David had recovered his balance.
"How are you able to do that?" David asked, staring at him with wide eyes.
"You and your brothers are limited by your earthly bodies," Donatello replied. "I'm not." He moved to the railing and looked out over the city.
In a moment, David joined him. "What does it mean, to not have an earthly body?" he asked.
Donatello sighed. "Usually, being a spirit without a body means you're dead," he explained. "I'm not. I'm just… trapped."
"Do you want to be free?" David asked.
"I've always wanted to be free," Donatello said. "But I'm certainly going to miss some of the things I can do here." For a moment, neither of them said anything. Then Donatello shook his head. "But we're not here to talk about me. We're here to talk about you." He gestured across the glittering skyline. "David, if you hadn't been sick, all of this would have been yours."
David raised a brow. "I would have been the emperor of New York?"
"Don't get snarky with me," Donatello said mildly. "What I mean is, you would have been able to climb this building and enjoy this view any time you wanted."
"We just flew here," David pointed out.
"Well, yes," Donatello said. "But only for the sake of expediency."
David carefully leaned over the railing to examine the sheer side of the building. "I would have been able to climb this?"
"Your brothers do it all the time."
David straightened up and looked at Donatello. "How do you know?"
"I live with them," Donatello said. "Sort of. I hear them talk."
"So when Raphael says you've always been there…" David began.
"I have," Donatello finished. "He's the only one who can see me. I don't know why."
David sat down, settling on the tiny flat space nestled against the base of the spire. "What am I supposed to be learning from you? I have a feeling it's more than just this," he said, and he made a gesture encompassing their journey from the sewers to the heights.
Donatello sat next to him. "This is what you're supposed to be learning, and please understand I'm only telling you this because you're me." At David's questioning look, he continued: "You're kind of a jerk to people. You know this."
"Yeah," David said, and he actually smiled as he said it. "I'm really good at highbrow insults."
"You are," Donatello agreed. "But other people don't feel good when you do that to them."
David looked down. "I can't help it," he said. "I - I feel so powerless, in my real life. I can't go anywhere or do anything. But I can dominate people intellectually, and I can make them feel the way I want them to feel. It's the only way I have any control."
"It sounds to me like you can help it," Donatello said, "but you don't really want to."
David didn't answer.
"What do you think would happen if you were nicer to people?" Donatello asked.
"They - they would take advantage of me," David said softly. "Donatello, I'm scared."
Donatello held him in a secure but gentle embrace. "How do you feel now?" he murmured after a moment.
"Safe," David said. "Cared for. Connected."
"So do I," Donatello said. He pulled back, slowly. "Your brothers need you, David. Not to sound arrogant, but they need the you that's like me. You have a latent ability to make people feel safe and cared for and connected. They've been missing this in their lives. You can bring it back for them."
"I can't live with them," David said.
Donatello gave him a playful push. "All those brains and you can't come up with a telecommunications system? I'm embarrassed to be pretty much the same person as you."
David smiled, just a little. "Do I get to see where you live? I want to see what my doppelganger invented."
"No," Donatello said. "But I will tell you, you have a submarine."
"Get out," said David.
"With depth charges."
"I hate you so much," David said. Donatello raised a brow. "I mean, I am so impressed and jealous."
"It's a start," Donatello said. He stood up and offered David his hand. "Don't drain me yet. You probably don't want to jump from here."
They flew back the way they had come. Donatello took them high, for a spectacular view all the way to New Jersey, before circling down to the astral shadow of Gentle Care Veterinary Clinic.
Leo and Raph were meandering the street, apparently having realized that the astral plane was completely deserted, and they were free to explore. They turned in amazement as Donatello set himself and his other half down by David's own front door.
"What the -" Raph started.
"I'll let him tell you," Donatello said, nodding at David and not letting go of his hand. Then he looked at his spirit double, and his expression turned serious. "David, listen. If you take what I think you're going to take, I won't be able to help you much after this. I'm leaving a trail to where I think I'm going to re-embody. Follow it. After that, you're on your own."
"Thank you," David said. "For everything. In case I can't tell the next you."
Donatello smiled warmly, tilting his head just a little. "You're welcome." He met Raph's gaze, then Leo's. "Bye, guys."
"Donnie, wait," Raph said.
But it was too late. Donatello embraced David with his free arm, and the light that had been building around their feet enveloped them both. A pair of bright peaks rippled, like two candles, before twisting into one.
What had a moment ago been Donatello looked out through different eyes. The fingers of his still-pale hands had merged into two thick digits, and a matching set peeked out from under his pant legs.
"No!" Raph was howling, as Leo held him back. "Donnie! Donnie, I -"
"I'm still here," Donatello wanted to say, but his head was spinning, as it hadn't the other times a piece of him had joined with David, and he couldn't get the words out. Slowly, he sank to his knees on the pavement. "Guys," he managed, in a wavering voice. "I don't feel so good."