Here’s the poem, The Hound of Heaven, mentioned in The Dark Divine by Bree Despain (Chapter 16). According to Wiki it was written by Francis Thompson in 1893 and influenced J.R.R. Tolkien.
I FLED Him, down the nights and down the days;
I fled Him, down the arches of the years;
Chuck and I are in love
“You thought you got rid of us, didn’t you? Well, you’re wrong.”