Thanks for you contribution,
William, and apologies for not replying sooner.
In terms of what you said:
While it's true that the SoF, especially Maedhros, should have acted more diplomatically, it's another matter whether they could. They were under the Doom of Mandos, most especially in any matter concerning the Silmarils and the Oath: "On the House of Fëanor the wrath of the Valar lieth from the West unto the uttermost East...Their Oath shall drive them, and yet betray them;" and I think those were drivers of irrational conduct, an independent dark psychological force somewhat reminiscent of the effect of the One Ring.
(It's also likely the case that, although M&M weren't as crude as Caranthir, privately they too thought of Thingol as a "dark Elf in his caves;" the thought of such an inferior possessing a Silmaril was intolerable to them.)
I think they could have acted more diplomatically; because they, unlike humans who eventually die of old age, have plenty of time to spare. This can be seen when they did not attack Morgoth for
centuries, despite the Oath being in force. All seven appeared to then have no problem letting it slumber for a time.
If they were prepared to be patient with their greatest enemy, who killed their father, could they not be at least equally patient with a fellow Elf?
Why not at least
try to get the Silmaril back by diplomatic means? At least it would give some public justification for any future use of force.
Sadly, you're probably right, in terms of what many of the SoF privately thought about Thingol. But they could have at least been
publicly diplomatic towards him, particularly after the scandal of two of them kidnapping his daughter.
