She’d already died once, she was not about to die again—Fate be damned—if she could prevent it. And she had many years to try and circumvent her new supposed Fate.
Echtehlien knew that in a different world she would have been born a male and named similarly—Echthelion. She would have been a renowned warrior as well as a very well-known lover of fountains (Hence the name of her House), and an incredible flute player.
She planned to live up to that pre-arranged and fantastical future legacy, but there were tweaks she could make, having been blessed with the memory and power of a previous incarnation as an accomplished witch who’d attended Hogwarts School of Witchcraft and Wizardy.
Also, she may have fallen for her fellow oathsman, Laurëfindelë, who would later be called Glorfindel, and she was not about to let either herself or him die if she could help it!
So Echthelien, Lady of the Fountain in the Court of King Turgon of Gondolin, had spent countless years in preparation for the largest Doom she could not prevent.
Ondolindë—Gondolin—still fell, yes, but she did not die fighting off Balrogs, and neither did her then unrecognized love, Laurëfindelë, who later became known as Glorfindel.
Instead, Ecthelien had researched—and what a pain it was to explain to the sons of Fëanáro that she needed access to a Balrog dead or alive—how to ward against said fell creatures. Somehow, she managed to magically ward Gondolin against the Balrogs, and the dragons that came were few. They were either swiftly dealt with or ended up fleeing from that massacre. Echetlien did not kill any Balrogs during the Fall of Gondolin, only one dragon, and her love—who had yet to be informed of her affections—guarded the rear of those escaping without losing his life in the process. Echtelien made it at last, terribly exhausted both physically and magically, to the secret tunnel which Princess Itarillë—Idril Celebrindal—had crafted, and together with the rest of the survivors—which numbered more than might have been—they all fled Gondolin for the Mouths of Sirion.
Eärendil, son of Idril and Tuor, still wed Elwing daughter of Díor Eluchíl, and his young wife bore him two twin sons named Elrond and Elros. The Havens at Sirion were still attacked by the remaining Fëanorionnath, though Ecthelien had miscalculated and she and Glorfindel were on Balar whilst the Third Kinslaying took place.
The Silmaril which Lúthien and Beren had stolen from Morgoth’s dark crown still made its way to the West, eventually being put high into the night sky as a star as a sign of hope to those who fought against the Black Enemy of All the World in Beleriand.
Sadly, the War of Wrath still happened.
The Great Army came from the West, led by the Herald Eönwë, King Arafinwë Finarfin of the Noldor, and Prince Ingwion of the Vanyar. Maiar, and much later on, the Valar themselves came to deal with Morgoth Bauglir who was once named Melkor.
Only, Ecthelien and Glorfindel fought in that Great War, and had many victories. Both still slayed a Balrog or two, though neither died in the attempt, and both won great valor for their houses, their king, and most importantly their kin.
After all, Ecthelien was not about to let her best friend and potential love of her life to fall to a Balorg, not if she could help it. And she could, if she planned it correctly.