I've been writing a story and it involves an Eevee who lives with the eeveelutions. There's a Sylveon character that's a newcomer to the town and is suuuuuper over excited about everything. I'm at a writers block and can't think of something to do to take up a whole chapter with her... Kinda filler-y, but I need to expand on her character specifically.
While the details you supply are a bit vague and I can agree with ShivaDF on needing more than just this aspect of you character, there's also other things to consider. Since you want her to be quirky you could give her a reason for being quirky. Here are some ideas that came to mind.
1) She could be happy about coming to that town.
2) She's wanting to meet someone there.
3) Maybe an event or something.
4) It can be her nature, but there should be a balanacer
Also, do you intend for any battling to be done with this sylveon? If so you can make a moveset to reflect her and show that she does know what she's doing.
But to answer your main question of expanding on her character understand that it's very hard to do that well in the introduction chapter. I wouldn't recommend that you expand on her now, but get intros out of the way. Later you can get into better details, past things, other parts of her, making her 3 dimensional, fleshing her out, showing how she is in the plot. Basically, I would have to say that wanting to expand on her now isn't a wise course of action. Unless we won't see her for a long while, I would say that you just put it merely as an interaction.
Also, since this chapter is filler, perhaps some random circumstance. Maybe a problem or a mentoring for a second. Learning something from the sylveon (like battling or something else). Possible helping this sylveon with some errand and/or issue.
But anyway I hope you can do well with it.
