Here's the explanation, from DC's Bob Harras:
"In TRINITY OF SIN: THE PHANTOM STRANGER #9, which hit stores today, readers saw The Stranger traveling to Hell on a quest to save the souls of his wife and kids. In next month’s issue #10, his search for his family will take him to Heaven. Queue Zauriel.
"Acting as a guide of sorts to help The Stranger locate his family, Zauriel has actually been connected to The Stranger for centuries … but why? And when The Stranger butts up against the strict rules of Heaven, there’ll be severe consequences – and it’ll be up to Zauriel to make sure he pays. Can Zauriel keep The Stranger in check long enough to avoid big conflict? You’ll have to wait to find out..."