From an interview with Ivy Mira Alonzo, author of Day of Hearts:
So what served as your inspiration for the novel?
When I was a kid, my lolo told me stories about the old gods and goddesses of our people, from way before Spain brought Catholicism to our shores. He didn't have a TV so when I visited him in the summer he would instead entertain me with stories about the sun god Apo's controlling ways, moon god Maya's rivalry with her siblings, sea god Aman's forbidden love affair… I adored them, and kept asking what happened to them next, and he'd always have a new story.
Day of Hearts is based on one of these stories, right? Did you do any other research into Philippine myths?
That's the strange thing. I started my novel as a project in college but when I researched the myths, I couldn't find the ones my lolo told me. Or the stories would be similar but the names or some details would be different. I began to wonder if he had been making it up all along.
You never got to ask him?
No. He passed away years ago. But I wrote Day of Hearts anyway as a tribute to him, using the Sun God's love story that he told me about.
Are there any other of his stories that you want to use, someday?
Oh definitely. He had a story about Diya, the goddess of love. That one day she disappeared, and the gods scrambled to divide her power among them. But they were bad at it, because none of them knew love like she did. And they couldn't inherit all her powers anyway because she wasn't dead, just missing, and after a long time, she returned, stronger than ever.
Did that show up in your research?
No. Lolo probably made that up too. But, I figure, he was just doing his part. His family liked to tell stories, and he grew up in this tradition.
Are you excited about the movie version? Isn't that coming out soon?
Yes, and I'm very excited. Casting's perfect. I had little to do with it, but the director showed me some scenes and it looks amazing!