Darksight's theme song (from Clearsight's POV):  One More Light by Linkin Park

Lyrics:

"Were there signs I ignored" (Signs that Darkstalker was going evil that she maybe ignored?)

"Can I help you not to hurt anymore" (this could be about Darkstalker feeling pain about his mom, or it could be about Darkstalker hurting others and Clearsight wanting to help him stop)

"We saw brilliance when the world was asleep" (NightWings are awake when most are not)

"There are things we can have, but can't keep" (their love?  Darkstalker's sanity?)

"If they say 'who cares if one more light goes out in the sky of a million stars'" (Darkstalker acts as if one or two lives barely matters)

"Who cares if one more light goes out, we'll I do" (Clearsight cares about lives, even if Darkstalker doesn't)

"And you're angry, and you should be, it's not fair" (Darkstalker is angry about his mom)