"Stay smooth."

"Only if you do. Enjoy the next seven years, man. They go by in the blink of an eye."

Leo shuts his eyes tight against the light of reentry as he materializes once again in the basement lab. It's shabbier and a little older than what he left behind, but so is he. "I did it," he says, unbuckling and disengaging from the time machine. "I did it, Big D! I mean, the other Leo really saved them, so technically he did it. Which means I did it. Damn, I'm getting a migraine."

Donald looks up from his work desk, his bearded aging mouth quirking up in a smile. "Good job," he says. "To both of you."

"Awesome, yeah," Leo says, sliding onto a stool. "So how does this work, huh? You're gonna get thin again, right? And, oh crap, I almost forgot. Little Me ruined my date with Janelle so now I have a dog, apparently. And-" The ding of the elevator interrupts him and he looks over to see his girlfriend, vivacious and beautiful as ever, walk into the lab. "Janelle!"

"Thought I might find you here," she says with a soft smile. "Oh, hi, Mr. Davenport. Invented anything cool lately?"

Donald grins at her. "I invented a machine that will take off my socks for me so I don't have to bend over."

"So… no, then," Janelle jibes, grinning back at him. "Leo, you almost ready? The movie starts at nine."

"Yeah, I'll be up in a second," Leo says, looking from Janelle to the time machine on the floor. "Just gotta finish up some stuff."

"Okay," Janelle says. "I'll be upstairs." She leaves the same way she came.

Slowly, slowly, Leo pivots to look at Donald. "She's here."

Donald tries to look confused, but it's not working. He knows what Leo just put together. "Yes," he says slowly, easing himself back in his chair. "Yes. She's here."

"And you're still… you know." Donald nods. "But that doesn't make any sense." Leo paces as he talks, walking in circles around the time machine. "Like I said, Little Me messed up my date with Janelle seven years ago. And you were gonna hit the gym more." He shakes his head, pulling out his tablet. "Look! I have this picture of the dog. I have a dog in this new timeline because Little Me messed up my date with Janelle. He did. He did it."

"Yeah, he did," Donald says, taking the tablet to look at the picture. Sure thing, clear as day, Leo with a dog and no Janelle. "But that was his timeline."

"But he's me," Leo argues.

"Yes and no." Donald looks guilty but not guilty enough, in Leo's opinion, not if Big D is telling him what he thinks Big D is telling him. "Time isn't linear, Leo. I sent you seven years into the past because you can change the future… but you can't change your own past."

Leo shakes his head. "What are you saying?"

"I didn't want to tell you," Donald continues, sounding even older than he looks, and that's really an accomplishment. "I wasn't sure you would still go if you knew."

"Knew what?" Leo can't stop seeing the boulders coming down, can't stop seeing his brothers and sister standing there, looking up… "No. No. Little Me saved them. Little Me saved Adam, Bree and Chase. I saw it happen."

"You're right," Donald says. "And Little You… the other Leo… he will grow up with them alive and well and all kinds of messed up crap will happen to them. But they'll be alive."

"He grows up to be me," Leo says. "I'm him and he's me."

"The past is a foreign country," says Donald.

"No!" Leo actually shouts. "I didn't leave California! I changed the past and I saved them and they should be here. Where are they?" Leo looks under the desk like he might find Adam, Bree and Chase hiding there, seven years older and thrilled to see him.

"The ripples in time were never actually going to affect us," Donald sighs, steepling his hands together. "You can change the future, but you can't change the past. You changed the other Leo's future, but you can't change your own past, Leo. We can't change what happened to us. But by warning them, by saving them, you created an alternate timeline…"

"No."

"... that will branch off from our timeline…"

"No."

"... and Adam, Bree and Chase will go on living in that alternate timeline…"

"No!" Leo shouts, knocking a box of Chips Ahoy off the desk. "I want them back! I want them back!" He knows he sounds like a child but he doesn't care. He waited seven years, watching Donald work tirelessly putting together this time machine, and none of it mattered, because it was never going to change anything.

"Time doesn't work like that," Donald says. "It's not one timeline, it's a million different parallel universes stretching out from the choices we make."

"You chose to lie to me."

"I had to give Adam, Bree and Chase a chance," Donald says, and Leo notices suddenly that he's crying, tears dripping into the tangled gray hair framing his face. "Even if it's in another time, even if it's in another universe."

Leo shakes his head. "What was the point?"

"You," Donald says. "Me. And Adam, and Bree, and Chase. Because of us, because of the time machine, there are versions of all of us that get to be happy and safe and go on."

"And what happens to us?" Leo says, looking up at him. "The other versions. The crappy universe where everything's horrible. What happens to us?"

"This," Donald says. "Life. You're going to marry Janelle, I'm going to eat those cookies you threw on the floor. And we'll wake up every day and know that there's an alternate timeline where Bree gets to go to prom and Chase gets to go to college and Adam gets to go to McDonald's. Can that be worth it for you?" He's actually asking.

Leo bends down to pick up the box of cookies. "I've gotta go," he says, keeping his head ducked so Donald can't see him wiping his eyes. "I'm gonna be late for the movie."

"I'll see you later," Donald says. Leo puts the cookies on the desk and turns around, heading for the elevator. He purposely tries not to look at the time machine. "And Leo?" Donald adds from behind him. "Just think of it this way: at least you got to see them again."

Leo walks away before he starts feeling too guilty about the wistfulness in his stepdad's tone.