To understand what happens next, you must first understand this:
Elured and Elurin's first memory of the sons of Feanor is of three of them making their father scream, and then the dreadful silence that followed. They remember being carried roughly through the halls to a blood spattered man who brusquely decided their fate.
They do not have context for this memory. They remember their father wearing a shining gem, but no one spoke to them of messengers or coming war. Even after it was over, few spoke to them of it. They have fragmented whispers of those determined to justify their part in a second kinslaying. They have Curufin's desperate rant to Celegorm about the importance of finding the jewel so they can help Feanor. They know of the Oath, and they know it hurts them and that it's likely why none of Feanor's sons can fully die, and they know their parents are dead, and they know all of these events are related, but no one has ever quite laid all the pieces out for them.
Elured wonders if all this silence is to protect their feelings and asks once, with unaccustomed hesitancy, "Was it Father's fault? The battle?"
Maedhros's head jerks up from his dinner. "No," he says furiously, "who told you that?"
"No one tells us anything about Doriath," Elurin mutters and stabs at his meat.
The next day, Maglor offers to sing them part of the Lay of Luthien. This does not, actually, answer any of their questions.
And set against all of this is their memory of Maedhros teaching them to fight and making time to teach them everything else he can. He is grim and weary mostly, but occasionally they can coax him into a smile that answers the question of why his mother named him Maitimo.
They remember Maglor singing them to sleep whenever they were ill or sad or anxious, and they remember the silly songs he sang to them to cheer them up after scrapes, and the healing songs after more serious injuries.
They remember Celegorm leading them to the kennels and talking them through how to help care for the puppies.
They remember Caranthir, normally distant, sitting down to teach them math and accounts, and how he had made the once dry subject seem exciting.
They remember Curufin, harsh, demanding Curufin, inspecting their armor and weapons again and again until he at last pronounced himself satisfied.
They remember Amrod and Amras teaching them to hunt and wheedling Maedhros into letting them serve their rare punishments together instead of separated.
They are told - frequently at first, and then less often - that someday they will be returned to their family. They believe this, vaguely, in much the same way they believe in the paradise they have heard described in the West. They do not think the speakers are lying, but it is a far off sort of promise that does not seem to have much to do with anything important.
(They have learned not to express any part of this sentiment to anyone outside of themselves. The horrified looks on everyone's faces are only funny for the first few seconds.)
And so when they make a habit of eavesdropping on the sons of Feanor's councils, it is not because they do not trust them, but because they know that there are blank spaces in their knowledge, and there is always hope that something will be filled in.
This time, something is.
They listen to talk about the ransom discussions, suddenly very real and very important, and about how those discussions have failed. They listen as someone, it doesn't matter who, states the obvious.
If Sirion will not surrender the Silmaril, they will have to try and take it.
Maedhros shoots the suggestion down.
Elured and Elurin back away from the place where the wall is thin and they can hear through it and look at each other.
They are not stupid. They can piece things together well enough.
Maedhros may shoot the suggestion down today, but sooner or later, the Oath will demand more, just as it demanded confirmation of where the Silmaril was.
The Sons of Feanor will attack their sister. Their sister, who does not believe they are alive. Their sister, whose advisors are telling her that even if they are still alive, they will have gone over to the Feanorians.
The Feanorians who, however reluctantly, tried to trade them for a gem to a sister who would not take the bargain.
In a safer world, this is the point where they would go off for a long ride to clear their heads. Here, they need a destination.
"Our continued existence, at least, is easy enough to prove," Elured points out quietly.
"And we can at least warn her that they are entirely serious in their threats," Elurin agrees.
They are not at all sure whose side their on at this point, if anybody's, but surely everyone will be better served by having all the facts.
As it happens, they're probably right, but they won't get the chance to find out.