Shoutout to jz81802 for getting 15 points for Team Poseidon (aka: Team Peanut Butter). The correct answer was Elias Veturius, A Torch in the Night, by Sabaa Tahir.

I don't know who said this one, but I know where's it's from and who wrote it. 10 for where it's from, and 5 for who wrote it.

Because Margo knows the secret of leaving, the secret I have only just now learned; leaving feels good and pure only when you leave something important, something that mattered to you. Pulling life out by the roots. But you can't do that until your life has grown roots.