You know, I've seen a lot of AU ideas where Adrien runs away from Gabriel and is more or less homeless on the streets of paris, and while those are an interesting perspective to explore and an excellent story to tell, they always seem to focus on how miserable and starving and out of his depth Adrien is. Like, running away is always described so bad that it really feels like he might have been better off living with his abusive father.
And I get why, an average kid in the real world would definitely not be having a good time. But Adrein Agreste isn't a regular kid, he's got superpowers. Sure, he needs to be in the suit for those, but the suit only has a time limit when he uses Cataclysm, as far as I'm aware he is completley fine to just run around as Cat Noir as much as he wants otherwise.
In my head, it makes sense that Adrien, being locked up and cooped up his whole life, upon being given this insane power, immediatly realizes he can use it to escape his dad. not temporarily, but forever. With Plaggs help, he can weave through the manors security. He can break out without even being seen. He can escape not just to go to school, but escape completely and totally. Afterall, what can a fashion designer do to stop a superhero?
And despite a lot of fanfiction that makes it so that they don't get nutrients when eating in their transformed state, there really isn't anything in cannon about that. And the citizens of Paris definitely wouldn't mind feeding their hero. In fact, if anything, I like to imagine that Paris rather fondly refers to the hero that seems to be nearly constantly on patrol as "Paris's Favorite Stray" or just "Our Stray Cat".
So thats food covered, and as for shelter, well, despite it not really being legal, there are loads of people who practically, and sometimes actually, live in the catacoms under paris. All he needs is to scout out sleeping spots beforehand in supermode, and I doubt he'd have much trouble.
The last thing though, is that realistically, no one can live alone. Being isolated would wear down on him fast. Especially because I imagine the main reason he ran away to begin with is because his dad wouldn't let him go to school, so again being isolated wouldn't be any better.
But the thing is, Adrien would only have run away because he knew that with Plagg, his dad can't stop him. So...realistically...who can stop him from going to school? He's already enrolled. At least until his dad reports him missing, and who knows how long that will take, he can enjoy the regular life he wants.
Cue what I consider the bread and butter of this AU idea: Adrien detransforms to go to school and makes all the usual friends and things, only he is WAY more free and happy, and at the end of every school day he gets out of the school building faster than anyone thought possible, in case his dad sends someone to stake out the school.
How does Adrien keep going to school if he's a runaway and reported missing? Simple: The Gabriel brand cannot afford the scandal, or the child protections investigation, that would come from reporting Adrien missing. And Adrien KNOWS that. So so long as he shows up for any photoshoot he knows his father isn't trying to use to ambush him, or escapes every time he's ambushed, then he's fine. And with the Cat Miraculous as a secret weapon, there isn't a lot Gabe can do. He can't even risk using Akumas to hunt his son down, lest others realize Adrien is gone.
Adriens friends at school know that Adriens homelife is weird. They were able to throw him a party, but not allowed to do it at his house, and Adrien insists no one ever talk to his dad. And he can be a little squirly on occassion, but no one guesses that he's essentially homeless for a long time. In the end, I can't decide if it should be Nino who Adrien basically shows his place in the catacombs too, or if Marinette realizes it via her "friendly stalking" of him.
Cat Noir though, is an even funnier part of this story, because there is NO beating the allegations that he's homeless. He is literally Paris's favorite stray. Chat is essentially constantly on patrol, so Paris gets to know their cat in a way that they just don't see ladybug. They still see Ladybug as the heroes leader and as Paris's savior and all that, they hold her in a LOT of awe. But with Chat, it's more casual. They see Chat everyday. He stops more muggers of old ladies than the cops and rescues more stuck pets than animal control or the fire department combined. It's not uncommon for especially busy parents to call out to Chat as he jumps between rooftops to ask him to pop in and watch their kids for a moment while they run an errand. Or for Chat to help a worker or deliveryman with a particulalrly heavy load if he happens to spot them struggling.
Ladybug is still the hero who purifies the akumas and makes everything perfect again, she's still Paris's savior. But Chat Noir is the cities lovable lifeblood, he fights akumas beside his lady, sure, but he also fights them by seemingly ALWAYS being available for a citizen to vent to, or to step in to stop a child being bullied and imaprt some lessons onto the children doing the bullying that they'll carry their whole lives.
Ladybug, of course, worries about her kitty. She's terrified she'll wake up one day and have a new Cat Noir just because her boy died of the cold shivering under a bridge, or wasted away without food. Boxes of pastries and other foods are often foisted upon him. And she never complains when Chat accepts food from resteraunts and vendors, because all she can think is that this is probably the first meal he's had all day.
Adrien, for his part, finds that the people of Paris, total strangers, make a better family than his father and that empty house. Andre the icecream man always insists he stop by for a scoop whenever he passes, and gives him love advice like a doting uncle or grandpa, sometimes about Ladybug, sometimes about what to do when/if he ever moves on.
The old ladies at the fabric shop on his morning patrol before school always pile him high with new scarves and hats and mitten whenever the weather turns cold, with stern faces and insistence that he better come take a catnap in the store if it gets too cold out there, leaving a window on the fifth story unlocked just for him, though he tries to never use it.
There is a cafe near the end of midnight patrols that always keeps a bag of baked goods and a massive cup of coffee waiting for him, and he always gives the manager the biggest hug he can in thanks. She always tousels his hair and frets, she's got boys his age she says, and she worries for his sleep during the school year with all his patrolling.
The italian place near his favorite hidden entrance to the catacombs always keeps a dish of some delicious meal or other warming for him, and the staff is always excited to see him, on their breaks, as he consumes plate after plate of pasta dishes, they ask him about his day and tease him about the details he feels he's allowed to share about school. They all silently catalogue every mention or lack thereof about his home life, and swear many a blood oath against the clearly abusive shitstain this poor hero seems to have fled from, though they know nothing that could help them narrow down who the bastard actually is.
Just.... an Adrien whose home is the city of Paris, who finds joy in helping others, and who gets back as much as he gives. Kinda like a reverse cryptid almost. Strange yes, mysterious even. But unknown or not understood? No, no they know the boy just fine, and they wouldn't trade him for the world.
