A 12 year old boy wakes up by a lake with no memories at all and is chased through the world by crazy people and demon hunters and ends up killing someone with a new demonic power

"Ok so let's take a recap! I have no memory of anything before a year ago, I escaped a military base and ran into an annoying smirking boy who has the ability to combust whenever he wants aaaaaaaaaand I just happen to control his opposite.. Water....... Lesson over!" Mind slated, Tide has no memory of her past but when she runs into a mysterious boy Flint she doesn't no how to react, should she kill him? Or use him to learn about the world she had been kept from?