Alicornutopia

The Sidereal Matilda couldn't be happier about him. XD

Dragon could not understand Promise for the same reason Bree could not type. Promise was not, in fact, speaking any of the languages Dragon knows; she was plain speaking (which is a weirdass superposition of magic sound). The magic superposition of the sound doesn't work on computers.

It's not literally impossible to understand the sounds directly, though - sort of the slicker more convenient version of what happened to Trinket. Trinket had no native language, heard-and-understood a lot of magic sound superpositions, and grabbed onto randomass conveniently pronounceable bits of them to cobble together an idiolect. Dragon heard-and-had-translated a lot of magic sound superpositions, and that plus Tinker-quality machine learning means she can now just (plain) understand Promise when she talks. (I'm undecided whether fairies in general all use the same vocabulary of plain speech. They could easily just not; it's not like they'd notice. Won't have to decide until Dragon runs into a non-Promise fairy.)

Dragon could have spoken to Promise, because the "in" end of plain speaking is just "if language is near a fairy the fairy understands it". (If you're curious, yes, this works on Draconic.) But she didn't want to have the awkward conversation delays implied by Armsmaster translating to make her part in the conversation obviously weird-in-some-way, so she was just quiet, until she thought she'd be able to manage.

Also if anyone's curious, Dragon is concerned that "Dragon" may count as her real name, and everyone who she's had to ask not to use it around Promise probably now thinks that her name is "Sandra" or something. Sarkany is what I named the walking-around-non-combat telepresence suit she's using.

I figured that was why Dragon did that. I think the fear is correct, right?

Yes, Dragon is her real name and AIs can be vassalized.

Is this canon? I assumed that she picked Dragon herself and her real name was something like "Experimental-AI-version-0.1" or something.

There's a certain threshold of what constitutes a name, which is why most mortals are not named "bun in the oven" or "one on the way" or "the baby".

I thought you couldn’t be named before you were born/hatched/whatever your species does. I wouldn’t think the first two would be likely whether or not they would count as names.

Her first human-style name that was meant as a name was Tess Teresa Richter, because she was originally "test three" and Defiant thought she should have a real name. We decided Dragon is what she was test three of, Worm itself never says.

.......What happens if Grendyne copies Addy? Would it be at all useful to do so, or would it just add a redundant extra layer to her copying?

Grendyne can't copy Addy. It's too meta, her magic tosses its hands up in disgust.