Not much, probably, he was never the geopolitics type. He never does anything wrong but sometimes that means he doesn't do anything. Has blanket permission to approve R&D but not to reject it. Worked as a doctor in some cloudy town while vampires some of whom he is willing to call friend snacked on humans. He wouldn't hate Maitimo but he wouldn't help him either.

"And your mother?"

Elspeth doesn't know the inside of her mama's head. Find out more information, probably, but Elspeth can't just go around learning literally all information, she is not a suitable repository for secrets. Consult Siobhan and Alice, probably, but they're not here.

"And we can't bring them. All right. What I am going to do is work up what looks like a powerful magical effort to break Doriath's wards for an invading army, use the cover of that magic to land a few dozen people from airplanes, have each of them find the nearest local and try, with the threat of being totally erased like the Iathrim know we did in Nan Elmoth, to coerce an oath to kill the King. Does this strike you as preferable to invading outright."

Has it somehow managed not to be common knowledge that he doesn't really have that threat on tap to deploy at whim? Anyway it seems implausible that random civilians will be able to do that. People who depend that much on their mates do not leave them undefended.

"I am expecting it's not common knowledge in Doriath, they don't talk to us! And I have weapons I can give them which Doriath does not know of. I'd be delighted to hear a better solution."

What's he even going to do with a headless Doriath? Still pretty much invade it?

Yes, but with a lot less resistance, probably. Does she have a better idea.

No but she's not going to follow through on his threat for him.

"I was not expecting you to."

And then a voice says in her head, uh, princess Elspeth?

Huh? Hello?

It's super rude to do this but I had to try. Can you help us? Everyone thinks you're working for the Noldo king but you weren't, ah, projecting liking him much, and there's got to be some way to stop the Enemy without handing him the only source of protection in the world, and I thought maybe we could secretly talk?

"I swear that if you tell them anything -"

Elspeth very much doubts it behooves her to hear the rest of that sentence.

She gives him a little tap to the face, just enough to knock out two-thirds of his teeth, and leaps out the window and takes off for Doriath.

They are not stupid enough to try to stop her.

Good. Where should I go? she inquires of Lúthien.

I'm not actually allowed near the border but I can tell it to let you in. And tell the guards not to bother you, though they will anyway if you mean any of us harm. So if you don't just think that and run on in.

As long as nobody's about to extort her she almost never punches people in the face! She doesn't have any harmful intentions as she races into the forest.

And meets someone who looks not-quite-an-Elf - taller, prettier, more inhuman. 

Hi. 

Hi.

(The initial messages about what happened are very confused. Finally a cringing and apologetic guard gives him a proper explanation. He laughs. Maitimo, being frantically attended to by a dozen healers, is not amused, and orders some people to drag him out of the room, which they do. He keeps laughing.)

So the only things I know about you is that you're a princess and hate the Noldor. Which, me too. Think you can help me prevent a war?

Elspeth doesn't hate literally all of the Noldor! Findekáno and Aredhel continue to seem fine and there are lots of them she hasn't met. The King's an asshole though. There is however a huge mess about the Silmaril and she does not know of any non-war options that don't involve handing it over. Maybe they could trade for it or something but it seems to be a particularly nonfungible item.

And then he uses it to destroy the Enemy and has a Vala-destroying weapon in hand and...tells us thank you have a good day?