So, this is the kind of AU that I love but don't see enough of; the team as kids, not necessarily related by blood but having each run away from home for whatever reason, and found each other to look after along the way. This will probably just be two parts, as I think the more I add to it the less it makes sense, or at least the less realistic it gets! But if you like h/c and don't care too much about context, hopefully this is for you.

Also, it doesn't matter hugely but the ages I imagine the gang to be in this are: Tony - 16, Tim - 15, Ellie - 11, Jimmy - 10, Abby - 9, Sarah - 6.

Enjoy!

...

It's raining outside when Tony gets back to the motel, so he runs the last hundred yards to the door and speeds in without knocking. Tim springs up in front of the kids, throwing one arm out, but deflates when he sees who it is that's entered. "Tony, you scared the heck out of us!" He scolds.
"Calm down, kiddo, I was drowning out there!" Tony flashes him an apologetic smile as he reaches down to ruffle Abby's hair. Tim frowns.
"You've gotta stop calling me that Tony, I'm only one year younger than you."
"You're 15 Tim, and that makes you a kid and me a grown-up."
Technically neither of you are grown-ups." Ellie pipes up over the top of the book she's buried in. "Did you get food?" She asks without lifting her eyes from the pages. Tiny lifts the plastic bag he's clutching with a grin. "Greasy Joe had a couple cheeseburgers going spare." Ellie drops the book.
"Seriously?" She scrambles over to join Abby at Tony's side. Tony hands the bag over to her and lets them pour its contents onto the double bed in the room. Sarah, who'd been on curled on the bed, crawls over to get in on the action.
"How'd you manage that?" Tim murmurs as the girls start bickering over chips.
"The guy owed me a favour." Tony answers, and before the younger boy can delve into that further: "Where's Gremlin?"
"Jimmy is out back. He found a snail colony that he wanted to document. And you know he hates when you call him that."
"Well we can't have everything we want." Tony shrugs. "Go find him for me?" Tim sighs.
"Sure."

It's dark out and honestly, Tim should've called Jimmy back inside a while ago. That's on him. But most of the time he just can't bring himself to interrupt the kid when he's having fun - it's so rare to see him smile that when he does, Tim just wants it to last forever. But of course nothing can. He pulls the hood of his raincoat tighter around his face as he leans out through the back door.
"Jimmy! Food!" There's no reply. He ventures out a little further, letting the door swing shut behind him. "Damnit, Palmer, I told you to stay right here." The snails are present, but the kid is nowhere to be found. Over the rain, he can hear faint shouting, so he slowly rounds the corner to follow the noise. There's a dim alleyway, and under it's lone lampost's flickering light, a man and a woman. The woman is screaming, swearing at the man, waving a gun. Tim swears himself, because crouching behind a dumpster wall just beside them is Jimmy. "Jimmy!" He hisses. No response. He creeps closer, reaches out an arm and tugs on the boy's sleeve. Jimmy flies back into the wall, knocking his head on the bricks. As soon as he sees who it is, he relaxes a little, but his eyes are still wide. "What are you doing?" Tim whispers before he can stop himself. "I told you to stay close, Jimmy-"
Jimmy shakes his head frantically. "Sorry, I'm sorry-" He hiccups and Tim realises he's crying.
"Ok, no it's alright - let's just get back to the others, ok?" He stammers. Jimmy nods but doesn't move.
"They're fighting." He says.
"I know, but it's none of our-"
A gunshot rings out.
"There, you piece of sh*t!" The woman cries out. Another gunshot. They don't talk anymore. Tim grabs Jimmy's arm, and they run.
"Hey!" The woman shouts and as they leave the alley, Tim turns to look. The woman is stood over the man - he's on the ground now, not moving - and her eyes, which are wild and angry, meet Tim's. Then they're round the corner and she's out of sight. He swears again, and again.

Jimmy has stopped crying when they slam through the door to their room. "We need to leave." Tim says, voice low and somehow not wavering.
"Woah, I know it's bad, but it's not the worst place we've stayed!" Tony laughs.
"We have to go. Now Tony, I'm not kidding."
Tony's face pales. "Ok girls, you heard the man." He scoops Sarah into his arms and Tim starts shoving Ellie's stuff into a rucksack.
"What? But dinner?" Ellie whines.
"There'll be other burgers, brainy." Tony teases, but Tim can see his heart isn't in it. "Let's go."
Ellie pulls her backpack on, grumbling, and grabs a handful of fries on her way out. Tim helps Jimmy get a coat on and grabs his own backpack, and then they run outside to join Tony, who's loaded the three girls into the back of the truck already.

It's not until they're all in and on the road, careening down the highway, that Tony peers across at Tim. Rain hammers at the windscreen.
"Wanna tell me what the hell's going on?" He mutters tersely.
"Do you trust me?" Tim whispers. He's not saying anything if he's going to be called a liar.
"Of course I do, McMysterious." Tony replies.
"Jimmy and I..." He takes a big breath. "I think we just saw a murder."
The truck swerves.
"Jesus, eyes on the road Tony!"
Tony levels the steering wheel. Then, levelly but through gritted teeth: "I'm sorry, I thought I heard you say that you and Jimmy just saw a murder."
Tim, absurdly, pouts. "For once in your life could you just take something seriously?" There's a long pause, in which he internally berates himself. He's about to apologize - Tony has looked out for them all this time, he shouldn't be unkind - when the older boy speaks.
"Tim, I- look, just tell me exactly what you saw, ok? You might be- misunderstanding something."
"Let me out." Jimmy squeaks, squashed in the back.
"Not now, Jimmy." Tony says absently.
"Tony stop the car!" Ellie cries, and then Jimmy throws up.

A long half hour later, all the kids have been cleaned up and Jimmy has been calmed down. Tony has also been caught up, and that had not been a fun conversation. Tim sits next to him now, Sarah dozing on his lap, the others tucked under a blanket on the backseat.
"What do we do now, Tony?" He whispers, and he sounds young. He is young, Tony thinks as he formulates as response.
"We find someplace new to stay." He whispers back. "And we lay low. She saw your face but she doesn't know anything else about you. She won't be able to find us that easily." He wishes he believes that.
"I'm sorry." Tim's voice finally breaks, and he shifts Sarah slightly to one side so he can reach a hand up and swipe at his eyes.
"Its not your fault. I shouldn't have left you guys for as long as I did-"
"Don't say that. It isn't your fault either!"
Tony sighs; this is an argument for another day, both boys wanting to take the blame. "Ok. Fine." He looks over the kids in the back one last time, and checks the mirrors for anyone else in the parking lot. There's nobody around. "Get some rest, kid."
Tim rolls his eyes, but then he closes them and stretches out, still holding his sister close to his side. "Goodnight." He murmurs, exhausted and already halfway asleep.
"Night." Tony replies quietly. Then, almost to himself: "We're gonna be ok. I'll make sure of it."

That night, he doesn't sleep.