Contrary to the described girl, another girl is making her way through the forest, only stopping to watch some ants walk around or give a pair of birds some space. She's skipping a little as she walks, though somewhat erratically, as she somehow manages to avoid all the mounds and twigs on the ground on her way to wherever she's going. 
Someone who's been watching her would know that she doesn't actually seem to have a destination. She's been around this area for almost the entire half day, watching caterpillars and deer and the occasional, unexpectedly diurnal owl. And maybe that's why she notices a different sound rather quickly. She takes care as she slowly draws to a halt and looks for the source of the noise.
She finds that source rather quickly, helped by the relatively quiet nature of the forest. But because shouting a greeting from here would probably be impractical and startling, she waits a bit, observing for a little while longer. Only after watching the other throw a few more small projectiles at the tree does she start walking again, swerving around other trees and careful to walk in a large arc away from the other in case her presence is sensed. By the time she finally gets to what she considers to be an appropriate position, a minute or two has passed. Stopping near a patch of small trees, so small and sparse they could almost be considered a clearing to a path, she opens her mouth and speaks.
"Hi! Excuse me..!” She starts off rather quietly considering how much louder she could have been. She also has a good smile, even though it's not the most radiant. It's genuine and simple in that way. “I was just passing through this part of the woods from the back, but I didn't want to startle you."
She’s still smiling, of course, her hands visible. She’s the opposite of threatening, though not in an extreme sense. She seems friendly enough, but hopefully that conveys to the other girl. That's the most important part of it, after all. 

The girl peers at her, her eyes bright. However, it's quite easy to see a flicker of concern pass through her eyes as soon as she registers the other girl's unhealthy look. Like she has an instinct to comfort someone, she almost leans forward as she reacts, barely stopping herself at the last moment.
Well, clearly, she's not going to just leave. That'd defeat the purpose, and besides, that wouldn't be like her at all.
The next time she speaks, it's after another small bout of thinking, and now her voice clearly gives off an aura of concern. "Hey, I'm sorry, but are you okay?" 

(I do like the font size conveying the volume of her voice :D)

Technically, the question is rhetorical, but this one happens to not have enough practice with those. So, she treats it like an actual inquiry, answering sincerely: "You look a little down. A little tired, too. I know I'm probably bothering you right now, but I don't want to risk turning away and being wrong to do that. So..."
She smiles brightly. "Other than leaving or something like that, maybe I could help somehow? Do you maybe want to talk about something? Or maybe you want to draw? I have a sketchbook on me that you could use!"

"Of course!" The teenager beams and walks, almost bounces, over to where the other is. Though, it's less like she's not caring to watch her step at all and more a natural jubilance that is just incorporated into her movements. In any case, she smooths her clothing behind her and plops down unceremoniously next to the other, tucking her knees in and resting her hands on either side. 
It seems she has a piece on her back designed to act as a cushion of sorts to sit on. Interesting.
She tilts her head slightly, keeping some words to herself temporarily to read any cues from the other on the situation, like whether Lydia wants to talk more, wants some quiet time, or things like that. 

By the time Lydia speaks, the other girl has untilted her head, since she's not an actual owl girl, and is mostly just observing the tree with genuine interest. But her response is so fast that it feels like she was definitely waiting for the other to talk. 
"I'm Manai!" she says. She turns her head towards the other and brings one of her legs closer to her torso. "Manai Chinami." She grins. "Now here's the expected response. What's your name, if you're okay with telling?"

"It's nice to talk with you, Lydia!" she answers, adding, "And to meet you, of course." She pauses for a little moment as if trying to recall what she wanted to say. "Oh, I just realized your name also starts with an L! I think that it's a really nice name. Though, uh, not directly because of what letter it starts off with." She gives a little laugh. "Sorry, that might have sounded weird."

Somehow, Manai's already getting used to the intermittent silence. She just takes it in stride and resumes a little pattern of occasionally glancing at the other girl and looking at a pair of bugs that just skittered past some nearby grass, presumably to strike a balance between looking entirely disinterested in the conversation or demanding an immediate response.

Manai's mouth definitely forms a little O on that one.
"Your...brother...?" she repeats, a little slower than her usual speech tempo. She too slowly brings herself to look at the tree, her eyebrows rising a little, slowly, like the translucent fog around a harbor at morning. 
But, she seems to snap out of whatever state she was in just as quickly. "Oh, I'm sorry!" she quickly apologizes. "I didn't realize." She raises a hand and smiles at the tree. "What's his name? Or, what's your name? I'm Manai, as you probably heard already! It's nice to meet you!"
Oh no.