Chapter Text
It all starts when Mac (or Ronnie, as he was known back then) and Charlie are 13 years old. (Well, Mac is really only 12, but that's almost thirteen, okay? And that's basically as good as being thirteen, no matter what Charlie tells you. Also, he's way more smarter than Charlie anyways, so it's basically like his brain is thirteen already.) They'd spent all morning scavenging coins from the fountain in the park until they'd each had enough for an ice cream. Mac grins as they walk home together in the afternoon sun, both their pants weighed down with dirty fountain water and stolen coins. Everything is just about perfect, right up until Charlie leans over and steals a lick from Mac's ice cream cone.
"Dude." Mac scowls. "What the fuck? That was my ice cream."
"Sorry." Charlie frowns. "I just wanted to test it. You know, in case it was poisoned or something. 'Cus of the stranger danger stuff they were talkin' about at school, remember? Like, adults are always putting poisons in candies 'n ice cream 'n stuff." He stops for a second, licking his lips in contemplation. "I think this one's okay though."
"Oh." Mac scrunches his nose. "Um, okay. Thanks then, I guess." Charlie grins at him. A couple of his adult teeth are still not quite grown in, and somewhere in the back of his head Mac wonders if thirteen is too old to not have all your teeth yet.
"What kind of best friend would I be if I stood back and let you get poisoned? What if you died? Who would I even hang out with? I’d be so fucking bored, dude.”
"Well, you're my best friend too, and I don't want you to get poisoned either!" Mac says. "Maybe I should test your ice cream and stuff too, just in case."
"Well, no, 'cus then we're back to square one with you getting poisoned. Plus, it wouldn't even matter if I got poisoned, 'cus I'm totally immune to everything. Vaccinations, dude." Mac thinks back to all the weird shit he's seen Charlie ingest over the years without batting an eye: batteries and bleach and various coins and bugs, and all the times Ms. Kelly has pulled him out of school to get him vaccinated against some obscure disease with a name Mac can barely pronounce, and decides this makes a lot of sense.
"Yeah, okay. You can protect us against poisons n' shit, and I'll protect us from physical threats with my sweet ass karate moves." He starts doing karate down the sidewalk, kicking his legs out and flailing his elbows, until Charlie grabs him by the shoulder. He stops, looking over at Charlie, who nods down at the ice cream cone in his hands.
"You're gonna drop your ice cream." Sure enough, the ice cream is tilting precariously to one side, threatening to fall out of its cone.
"Oh, shit! Thanks, Charlie."
It quickly becomes a part of their routine. Whenever Mac is eating something, he lets Charlie test it first. He slides his lunch tray across their table every afternoon, waiting impatiently as Charlie takes a bite from each little section. Almost instinctively, he holds out his fries for Charlie to test a few whenever he gets fast food. When they come home from trick or treating that year, he leans against Charlie’s shoulder as he methodically examines Mac’s candy for razor blades and holes in the packaging before handing them over for him to eat. Neither of them ever get poisoned, unless you count the time Charlie found out the hard way he was allergic to sesame seeds, which Mac thinks is a pretty good sign that their system is working.