All That Lives Must Die (Mortal Coils No. 2)

Eliot and Fiona Post are twins caught up in an epic custody battle between their mother's and father's families. Their mother is the immortal goddess Atropos, the eldest Fate, and their father is Lucifer, Lord of the infernals, a diabolical fallen angel. The families have put them through rigorous, life-threatening challenges, and together they've risen to combat them in amazing ways. But now they are facing the greatest trial of all?high school.