"I meant no insult!" Dodge ball of lava. "I don't intend to interfere, you said no!" Dodge house-sized spear of ice. "I'm leaving peacefully, okay, so stop tearing up the tile!"
"You'll respawn at home. No permanent damage. You interrupted an important meeting, you need to learn a lesson about territory, mountain bitch." Dodge- no, fail to dodge a thrown tree, and then another ice ball. The next sphere of magma is what destroyed that form.
She wakes up, stripped of all her tools and enchantments and even clothes, and groans in pain.
Medevac proceeds. Mountain is asked to put the nuclear plant back where it was before and remove your heat sinks and so on now that Behemoth's gone, thank you very much. They might even be able to start it back up in a month or four. The planes to take capes back home come and go and eventually Glam and Mountain are in New York again.
And Glam draws Mountain aside, which by cape standards is "floating around somewhere," and asks, "Is there something you think I'd be interested if you told me?"
"I know how your power works. I had a guess the first time we fought and knew for sure after that time we sparred. I hadn't planned to do anything with this knowledge, but against Behemoth you want every advantage you can get."
"In my homeworld there are several types of Fair Folk who can do - illusions that work until you realize it's a trick. Working with expectation. I had to fight some, once, and your power struck me as a very similar kind of thing. I know perfectly well that you'd be ruined forever if anyone but me figured it out, so I have no plans to tell anyone unless you go hard villain."
"I'm not out to get you. Perhaps I should have told you I figured it out. I didn't- I'm not good with people. Social things."
"...Well, I know how to keep trade secrets, at least. You have to if you want to stay ahead as an enchanter."
"Uh. Only because I know your one true weakness, bwa-ha-ha. I was trying to act exactly as I would have if I didn't know about it. So think of it like you won against someone with my exact powerset and limitations who didn't know your weakness."
"Me neither, really... 'Continue being nowhere near as terrible as the Slaugherhouse Nine' is a good start?"
That's some upset body language alright... "Someone I knew for ten years surprised me. You never really know."
"And I don't expect to threaten you into anything or give out your secret without a damn good reason."
"But you do realize those are two completely different expectations, right? Out of the however many millions of people currently live in the United States, there are only nine who are, well, the Nine, whereas betraying secrets, or even letting them slip, is much more common. You have ultimate blackmail over me."
"Yes... You have ridiculously strong potential if you keep winning against powerful opponents, and from what I've seen you're actually a good person. The world needs powerful good people. I'll be honest and say I would probably use the blackmail if you suddenly became a genuinely evil villain. But you're not and I won't."
"Which still leaves me needing to trust you. Which, well, I won't have much of a choice there, will I? And you also look like a good person, but it feels awful that I never got to choose."
"Sorry, I suppose. If it's any consolation I think I am really quite unusually likely to figure it out. I got hints when feeling the world and I'd encountered something similar before."
They sigh. "So... Are you going to use that now and tell me to stop, I don't know, stealing stuff and humiliating the Protectorate?"
"No, or not unless you start carrying it too far. But aren't there dozens of high-profile villains all over the world - in this country even - that could use humiliation a lot more than the Protectorate?"
"Very much so, but unlike the Protectorate, they don't pull their punches, so I need a good enough rep to fight them. It's slow going."
"I could help with one, and give you most of the credit. Have you started that web show?"