Sakura wouldn't have given the snake in the patchy dirt a second glance if it hadn't sparkled when it startled while she walked down the path it was sunbathing on. It's a dull, ugly green in color, and who'd want even a regular purple ekans when you could have a nice, cute pokemon that can actually be friends with you like her nidoran? But even the lamest and jerkiest of pokemon were worth something if they were shiny. And this one's so tiny it must've only just hatched, which is probably how come nobody else caught it already. Adult ekans can be dangerous, but the babies haven't got venom yet, just like they haven't got a rattle, a fact all the more obvious as it hisses with all its might and there's not even the hint of any complementary sound from the tail.
The baby, unfortunately, seems to have been born with just enough sense to know that, and doesn't stand its ground and have a proper battle. It wiggles away between the rocks, but Sakura's been running around the boulders here practically since she was born too, not like there's much else to do around Cerulean, and she doesn't have to be as careful about where she's running as she would if she was chasing something like a spearow. Ekans aren't pokemon like spearow and nidoran and mankey and pikachu who actually have family and friends they can run to for backup. In fact...
She jumps between two boulders and lands to see a fully grown normal ekans in the path of the shiny baby. Ha! In fact, far from caring about each other, the worst thing it could do is run into another ekans. The cold-blooded thing would just gobble it up like any other prey. But it hasn't noticed, still slithering obliviously straight for death as it hisses and hisses in what might be the least believable bluff ever, and that ekans isn't going to have any interest in her with a meal already trying to jump down its throat, so she keeps going while pulling a pokeball out. If she's quick, she might be able to catch it right out of the big one's mouth.
The big one coils up suddenly, rattle going furiously. Is it startled by the sparkles? Probably hasn't seen a shiny pokemon before and it's scared. They're not smart like some other pokemon, that's part of why they don't even know their own families. It opens its mouth wide, showing off dripping fangs, and the oblivious little baby still doesn't slow.
The little ekans slides into the coils just as the big ekans springs at her.
Pokedex and real-life inspired fic.
Silver: It always hides in grass. When first born, it has no poison, so its bite is painful, but harmless.
There's also a couple parent and child rattlesnake pictures and video around.