"Don't say it. Ever. Don't communicate it in any way." But someone else could still figure it out the same way she did. "Can you refill metalminds?"
Promise is very, very paranoid about her god of destruction. But when she's got some of her metalminds filled up (and her tinminds carefully plenty empty enough to deafen her for days and sharpen her sorcery if she needs that), it occurs to her to ask if it can just... give her Feruchemy. Entire. No extra spikes. It tries to convince her to take Alendi's spike instead, but she wants it before she gets there; so.
Now she's a Feruchemist.
She acquires a coppermind, a little one, which she wears as a discreet navel ring hidden under her dress; and with Yellow serving as a test master-de-jure, and Promise deafening herself with tin, they test the ability for Ruin to transcribe conversations into the coppermind while she taps it, receiving the words in real time but without any possibility that she will be ordered. It works; Yellow cannot make her flap her wings that way.
She also acquires a few toerings, hiding under her shoes, piercing the skin, filled up with free cheatery luck and speed and luck and health and luck luck luck.
This is important because she wants to have a conversation with Alendi. Before she kills him. She's probably going to have to make (let) Ruin kill him.
She doesn't want to have to call Ruin to do something suddenly, not with its penchant for improvisation; so she works out its initial orders and likely contingencies in advance.
She gives Yellow a set of instructions, and deafens him with sorcery she can reverse later; she only needs his voice, not his presence.
Spellwhip stands a safe several miles back, and waits, allowed to do sorcery again and cooling the air.
And Promise makes a gate where she expects Alendi to be.
She's seen his office before.
It settles. She motions to Yellow.
"Hold," Yellow commands.
And Promise peeks through, invisible and deaf and sped way up and very lucky indeed.
He makes that one surprised face and goes, "wuh?" At least to the extent permitted by the order.
"Obey Promise as if she were your master," continues Yellow.
And Ruin has a job to do now, too.
"With the caveat that you may enforce no orders, trigger no prearranged contingencies, tell no lies of commission or omission, and achieve no volume that could conceivably attract attention from anyone who is currently unable or unwilling to act in my interests over yours," says Promise, "you may speak."
"You told me," she says, "to enjoy being stuck on the world with the god of destruction, didn't you?"
He's visibly aging again.
"Clearly." She stalks forward. "So. What did you do, and why did you do it, starting from whatever you think will be most interesting to me?"
I brought some materials over that I thought would be useful. Nothing more important than atium, though.
I created some lerasium.
I replaced every plant I could see—which was quite a lot—with an identical one. I'll have virtually everyone as a vassal soon.
I remade things from old Scadrial. Especially the fluffy animals."
Damn this completeness order.
The lerasium isn't hidden yet. You can find it in a drawer to my right."
"...Because of whatever reason you tend not to like killing people?"
"You got Nighteyes killed. And Thorn, though him I won't miss. You would have killed me and Spellwhip and Yellow too if you'd had your way. If you were willing to try it after three centuries during which we muddled along pretty peacefully and I did you no injury you will eventually try again. So, not the general case. You. In particular. Is there any reason I shouldn't kill you?"
"Nope. I got nothing. There is absolutely no reason you shouldn't kill me."
She is still Promise.
"I'll give you a couple of minutes in case you think of something."
He doesn't expect it to work.
"Are you telling me you can't think of a use for two minions with power over all fairies?"
She shakes her head.
"Kill him," she whispers.