The story behind her is a little long and complicated, and due to the circumstances I myself don't really quite know much of anything about her yet. Her name is Ilkurna.
Four songs that have had heavy ties to her by some means:
MrCrackles - Fall of the Princess (Aria pt. 2)
Skrux - Universe (Mashup) - Key part is chorus "Light up this fire before you come rushing"
Socratic Brony - The Fall - 3:55 and onward
Krewella - Human
L.M.Wub - Bright Shadow
Each song has triggered something that revealed vague information about her, or events. Most keep pointing back to an attack against her.