Margo's face shriveled and twisted into something nasty as her brother spoke. He was irritating her now and it made her want to bite him, but the girl also didn't much like getting in trouble and she knew that biting was off limits. Perhaps when she grew older she'd come to realize that he wasn't the one in the wrong here, that lying had consequences and sometimes that consequence was being called yucky. But in this moment her underdeveloped brain wasn't able to comprehend that anything could ever be her fault.
The Valle child couldn't figure out a way to lie herself out of this without further condemning herself into a deeper corner. What could she even say? That the bird was invisible now and bird poop was actually really good for your coat? She wasn't able to think fast enough for anything like that yet, so she settled on sticking her tongue out at the boy and responding with a classic.
"No, you yucky."
It was then in that moment that Margo realized she was growing quite cold out here in all this bird poop. Cold and angry, not the best combination for someone so young.