I've kind of had the assumption/theory/whatever that Wander and Sylvia had been traveling together and been partners for only a little bit of time before the show started, this being the reason for why Sylvia was still taken somewhat off-guard when Wander wandered off to greet the Watchdogs. And, slowly, we see Sylvia get used to his antics and understand that he is most certainly going to run off.
In the pilot, though, their relationship already feels really strong, like they already know each other well, Sylvia just shaking her head and smiling when Wander gets distracted and acknowledging Wander's ideas. It felt very sweet.
I'll just keep it short and sweet and say that I love the growth and exploration in characters' relationships throughout the show.
I also love how unapologetically irritable this girl is. For what is essentially a cutesy crafting game, the happy-go-lucky protagonist who's always in a good mood is not present. Sylvia is not happy to be here, managing her stress is a very large part of the game, and she has appropriately frustrated poses for a game that is, when you get down to it, about working in retail.