SAN FRANCISCO — After two months of missed rent, it was the knock on the door that the family had been dreading. Eviction brought the prospect of homelessness after months of living on the brink.

But little did they know that the man handing over the eviction documents, John Hebbring, was homeless himself.

“Believe me, we see the irony,” said Mr. Hebbring, whose job it is to deliver eviction notices with his girlfriend, Kim Hansen. Together they live in a 50-year-old trailer infested by rats.