(A lot of this is copied from an ask I answered earlier, but I liked it well enough to make it its own post. Mostly because I think I've done some really cool things with the character writing in To Bind Our Echoes That We May Be Whole, and I'd like to have that discussion a few steps removed from the earlier context.)
Anyways, I've mentioned before that I write Lace as a very specific type of young adult--one who has had her physical and emotional growth actively sabotaged by a narcissistic parent.
That said, just because she's not written to be a child, doesn't mean that others perceive her as an adult (whatever that means, in this buggy world and context). In fact, most of the characters in Echoes have expressly called her a child at some point in the comic.
Hornet in particular is guilty of this. She means well, but she's making a lot of assumptions about Lace's wants and needs, many of which are incorrect (and even harmful to Lace).
This is showcased most strongly in Ch6, in her conversation with the White Lady.
Hornet: Lace is of no threat to you, Lady.
The White Lady: No… she is far too frail, with that brittle shell of pale silk. Yet her fierce heart blazes, even to my wavering sight.
Hornet: Even knowing it would damn her, she cut herself free from her creator’s malignant web. When I chose to pull her from the void, I shouldered a duty to see her maintained.
The White Lady: It is honorable of you.
Hornet: … Or perhaps cruel, to bind her to myself, even figuratively.
This conversation has a lot of layers to it, including situating how both Hornet and the White Lady perceive Lace.
However, less apparent is the fact that neither Hornet nor the White Lady even broach the question of what Lace might actually want. The Lady asks the intentions of the Green Prince, Shakra, and Hornet herself--but completely omits asking about Lace's goals. And Hornet proves no better in this regard.
In fact, there is only one person in this entire comic so far that has asked Lace what she wants--and that is Hollow (Ch5):
Lace: Sigh. Nothing for a bad dream but to let it run its course. Perhaps next I’ll see my mother’s severed arm!
Hollow: Do you wish to leave?
Lace: Of course! But since when does what I wish–
That is the reason why she became fond of them so quickly--because they ask and, if possible, accommodate her. And, just as importantly, she reciprocates that care back to them.
This bare minimum support has also given her the confidence to begin setting boundaries with other people. Lace's dislike of being called a child has been present in the comic since almost the beginning--it's the thing that she loses her temper over with the Green Prince (Ch2). However, it's only been in the last two chapters that she's been willing and able to express that to others in a constructive way--first, telling Shakra that she is not a child, and to please respect that (Ch8); and then telling the White Lady to consider her Hornet's peer, not as a child to be coddled (Ch9).
Lace: Please. Spare me your condescension.
Lace: Do you issue the spider such inane warnings? Or is this concern exclusive to one such as I?
She's not going to stand for that treatment from Hornet for much longer either... But I'm sure none of that's likely to come up when they go on a girls trip to Deepnest, right?
Hollow Knight Fanart Masterpost