Kids didn't come to the beach regularly – they came in droves, of course, but only on vacations. This one was an oddity from the start: school had been in session for months.

Not that he needed the help. His hair stuck straight up from his head in weird spikes, and he was making faces at a stuffed tiger when Lilo first saw him, standing over a partially-completed sandcastle.

She immediately decided she liked him.

"Psst!" She stage-whispered from the treeline, Stitch perched on a branch above her head.

Lilo was skipping school.

So as long as she was here she might as well have some fun, right?

The kid didn't react immediately, but he must have heard her because a minute or two later, while his parent's backs were turned, he made a break for the trees.

"Psst!" She whispered again.

"Who's there?" He practically shouted.

Lilo's eyes darted back and forth, startled. "Shhh! You'll alert the sensors!"

"What sensors?" The boy said, thankfully a little more quiet this time, making a rapid survey of their immediate surroundings (mostly bushes and beach). "What's going on? Is it aliens?"

Lilo's eyes widened. "How did you know?" She whisper-yelled.

"Where are they?' The boy said. "Don't worry, I'll protect you! I've got a ray gun! And a tiger!" He made growling noises, holding the stuffed tiger aloft.

Lilo's eyes narrowed. She scoffed. "Yeah, some protection that'll be." She said contemptuously.

The boy's eyes narrowed in return. "Yeah, and what do you got? You're just a girl."

Lilo began to get angry. "Stitch!" She called. Said alien jumped down obediently to the top of Lilo's head, and made a menacing face, just because.

The boy immediately forgot all grudges. "Wow! Cool! Is that an alien?"

In face of his enthusiasm, Lilo's anger melted away. "Yeah! This is Stitch. Show him, Stitch!"

Stitch – who tended to look at least semi-normal unless told otherwise – quickly protracted all six legs and countless poisonous spikes. "Aloha!" He waved.

"Cooooool!" The boy said. "Hobbes can't do that although Hobbes is way better at pouncing."

Lilo magnanimously ignored this posturing and said, "So are you gonna help me find the sensors or what? Jumba said if I found all of them I'd get a peanut butter sandwich!"

"Blergh. Does this 'Jumba' of yours have chocolate frosted sugar bombs?" The boy said.

Lilo wrinkled her nose in thought. "Maybe?" She shrugged. "He has tuna too!"

The boy traded a look with his stuffed tiger. "I guess. Better than hanging out with my parents, even though you're a girl."

Stitch growled threateningly, poison spikes sticking straight up, and Lilo frowned.

"Fine, okay." The boy sighed generously. "I guess we'll play along with your stupid game."

~!_!*!_!~

Jumba's sensors were actual sensors, spread out all over the island in each of Lilo's favorite haunts. It was a birthday present for Nani, mostly.

They were disguised, however, as ordinary objects: A bouncy ball, a coconut... Stitch could sniff out the difference, but this boy seemed surprisingly adept at figuring it out, too.

The first one was at this beach, disguised, as it turns out, as a very cracked and ugly seashell (so tourists wouldn't pick it up). The boy told Lilo his name was Calvin and his tiger's was Hobbes while they were running away from the beach as quickly as possible, having reassured his parents briefly they were still there. His mother was sunbathing and his father was attempting – key word, attempting – to surf, so both were distracted enough that they hopefully wouldn't notice he was gone until it was too late.

Lilo glanced sideways at the tiger, which appeared to be keeping up rather better than a stuffed tiger really should. It also looked startlingly real. They were digging on Pudge's cove, looking for the second sensor – Lilo promised Pudge she'd be back with a peanut butter sandwich soon. If Hobbes was real, well, she'd seen stranger things...

"I sold the planet to aliens once, you know. They didn't look very much like Stitch though." Calvin admitted, not helping her dig.

Lilo swatted him. "Dig!" She said. "They're on a timer, you know! If we can't find them by tonight they'll start tracking me constantly!" The horror this statement inspired prompted Calvin to dig with renewed vigor, even though she probably could have gotten Stitch to do it in a fourth of the time. Oh well. "Anyway, you can't have sold the planet, because it's a nature preserve for mosquitoes. So there." She said, with an air of authority. She knew these things. She lived with three aliens, and talked to several others regularly.

"Who said?" Calvin said, not digging any more. "Besides, mosquitoes suck so why would anyone make a preserve for them?"

Lilo shrugged, unwilling to admit that she really didn't know. But still. "Stitch is an alien so he knows, right? Besides, the President of the Galaxy said so."

Stitch nodded. "Ih." He said decisively.

"Why can't he talk real well?" Calvin said, staring at the blue alien.

Lilo shrugged again. "Something with his teeth or something."

"Huh." Calvin stared. "But Hobbes can talk and he's got the same sorta mouth!"

Lilo glanced over at the tiger, who, indeed, was yawning and appeared to have the same sort of mouth as Stitch: Lots and lots of teeth around a cavernous dark hole. "I dunno." She said. "Dig!" She turned to the apparently-not-stuffed tiger as well, glaring. "And you! If you're real you gotta dig too." Hobbes heaved a huge sigh. "Fine." He said, mostly because she was a girl. She was rather cute.

(When the police finally tracked them down three hours later, they had found four of the ten sensors, Calvin's parents were worried sick, and Nani was about ready to strangle her erstwhile sister.

They'd played a game of Calvinball, talked about o'hana and other planets, and decided that Hobbes was an alien.)

Ten years later, when they'd both grown up a bit and Calvin had all but forgotten about that strange trip to Hawaii, Lilo showed up in a spaceship and a flowery space suit and offered Calvin a ride. "After all," She said, grinning at Hobbes, who was no longer the tallest of the group, "You aliens have got to stick together."

Calvin's smile was like the stars he'd soon be seeing up close. "Thanks." He whispered, staring in awe at her space ship, before saying, wistful and triumphant all at once, "Let's go exploring!"

So I got the idea for a Calvin and Hobbes and Lilo and Stitch crossover and decided it had to happen, no matter what. I only wish I were better at writing because I just want an entire universe where Lilo and Calvin are best friends and they just casually accept Hobbes and Stitch who become best friends too and they just spend the rest of their lives exploring the universe together and being snarky best friends and and and

Are these not the two most perfect, cross-over-able series ever?

Oh and for actual notes: I have incomplete knowledge of both series so if anything is off, sorry. I haven't been able to get a hold of all the Calvin and Hobbes books and I just haven't watched the sequels+spinoffs of Lilo and Stitch.