My Twin is a Darkling?

There are two brothers who live completely different lives despite being twins. One roams about during the day. The other prowls at night feasting on flesh. Both have been exiled from the paradise known as "Lover's Climb" which lays atop a dangerous mountain top location. The daywalker beleives his brother is dead and atones for the murder of an older girl in the village which he used to call home. He had not killed her, but the blame burns on him like a mark.