My favorite headcanons for caitvi are ones where they met as kids/teens, by far
Like it's so fucking cute, the idea that Caitlyn would be immediately drawn to Vi due to her curiosity, and Vi can't help but be smitten by Caitlyn's atypical behaviors and willingness to explore new concepts and experiences and ideas.
Just like when they meet as adults in the original universe, their backgrounds should make them incompatible, but there's that inexplicable draw that brings them together.
Imagine Caitlyn tags along with Jayce to his visits in the undercity without telling her parents and can't stop staring at the pink haired girl she sees there at the shop, just hanging around, and they meet eyes, and BOOM, instant connection. Vi also sneaks glances and realizes she's never seen a Piltie girl her age this close before. She wonders if they're all this pretty.
Imagine Vi is sneaking around topside to catch glimpses of Caitlyn, because she feels like she shouldn't be so drawn to a Piltie, but she is anyway.
Imagine one day Caitlyn actually catches sight of Vi across the street as she tries to remain inconspicuous, but Caitlyn would recognize that pink hair in a heartbeat. Imagine she sneaks away from her mother or whoever she's with in order to go talk to her.
"It's you," she says, shy yet bold.
Vi, of course, tries to play it off. "Dunno what you're talking about, topside." But the blush on her cheeks tells another story.
Caitlyn ignores the very obvious attempts at ignorance. "I've been wanting to come visit the shop again, but it's hard for me to find the chance to get away from my mother. She's kind of overprotective."
Vi decides it's best not to play dumb, but can't completely be honest about wanting to see her as well. "You're sure you wanna share about your life with me? Maybe your mom's got a point, shouldn't associate with undercity trash and all."
Caitlyn frowns. "I don't think you're trash. That's silly. Why would you call yourself that?"
Vi is caught a bit off guard. "Isn't that what all you Pilties think of us?"
"I certainly don't." Caitlyn cocks her head as this leaves Vi without a response. "Why are you here, anyway?"
Vi stumbles around in her head for an answer. Shoves her hands in her pockets. Kicks a rock aside. Shrugs. "W-why are YOU talking to me?"
This makes Caitlyn smirk. "I DID say I've been meaning to come back to the shop. What do you think?"
"Dunno. Could want a number of things there." Vi has been staring at the ground but peers up at Caitlyn here. "Give me a hint?" The barest of upturned lips.
This makes Caitlyn break out into a genuine smile that steals Vi's breath a bit. "You're kind of adorable, you know that?"
"Are so." Caitlyn tucks a strand of hair behind her ear. Can't help but think the girl's freckles compliment her blush well.
Vi rolls her eyes, trying to pretend her brain isn't setting off fireworks. "I don't even know your name."
"Would you like to know it?" Caitlyn says, tilting her head.
"Since you insist on teasing me, I think it's fair."
"But you make it so easy," Caitlyn giggles. "Alright. I'm Caitlyn."
"Caitlyn," Vi breathes. Shakes her head. Clears her throat. Thrusts her hand out, scuffed up palms and knuckles and all. "I'm Vi."
"Vi. Pleasure to meet you." Caitlyn takes her hand without hesitation, notices how rough they feel compared to hers, incredibly intrigued.
"Caitlyn!" A voice calls. The girls both turn. It's her mother.
"Shit." Caitlyn breathes.
This makes Vi laugh, surprised. "Didn't know princesses could use words like that."
"Oh, hush." Caitlyn looks back at her, panicked. "I have to go. I'm sorry." Her eyes shift so they're alight with mischief. She jerks her head towards her mom. "You've got a talent for sneaking around, I assume?"
"Wait until we're out of sight. Maybe if you're good enough, you can stay under her radar." Caitlyn smirks. "Maybe you could teach me how to sneak about myself. Could come in handy."
Without giving Vi a chance to respond, she turns away, skirt swishing about.
And if Vi does exactly what Caitlyn says, following her home out of sight, and later taps at the same glass doors of the balcony she sees the girl disappear into after a while of spying, no one is the wiser. She figures she doesn't need to tell Vander what she's been up to just yet.