It's called Arkenstone of Erebor. Arkenstone is a person, female, of course. Arkenstone steals lines, joins Thorin's Company, is Thorin's love interest, is described as the heart of the mountain, makes Thorin too nice, makes Gandalf OOC enough to sputter and be at a loss for words, has multicolored eyes on occasion, badly written fight scenes, a weapon named Dark Star, can create a boulder out of nowhere, has a sorry lack of description, puts a bracket in for no reason, has no explanation for her powers and abilities, creates the mini-Balrog Blain, makes Thorin uninteresting, has unmarked scene changes, gets angry over the continuation of the quest, messes with geography by thinking she can run to mountains from Rivendell in a few minutes, narrates from first-person point of view yet still describes events that Arkenstone was not present for, and calls herself Arkadia for no reason.

Enough charges to kill?

Coordinates: http://www.fanfiction.net/s/9495401/5/Arkenstone-of-Erebor