At one point in The Apocalypse of Elena Mendoza, when Elena visits a hospital to heal someone, she meets someone who seems to know a bit more than he's telling (highlighted for emphasis):
Henry didn't blink. He stood there with his hands in his pockets and listened. When I finished, he said, "It's always the end of the world, isn't it?"
"Nothing. Look, I can't tell you what to do. No one can, though trust me when I say that everyone will have an opinion. You have to do what you think is right. Forget the end of the world, forget saving humanity. Those things aren't your responsibility. The only things you can control are the choices you make, and that has to be enough."
"How do you know?"
"This is one area I have a little experience with."
The Apocalypse of Elena Mendoza
This thread isn't picked up again, with Elena instead focusing on finding out the motivations of David Combs (who turns out to maybe be a bit of a red herring).
However, it seems way too suspicious to be coincidence. Henry claims that the woman in the room is his grandmother with Alzheimer's, but if the things he says are supposed to be about caring for someone with Alzheimer's, they sound odd at best.
Who is Henry, and what is his connection (if any) to all the events surrounding Elena?