Homeless Teddy came back! He actually was on our back porch the other morning, so I whisked him to the vet for a checkup. He wasn't thrilled to go, but he warmed right up to everyone once we got there.
The downside is that he turns out to be FIV positive, the feline equivalent of HIV, but has the potential to live out many happy healthy years as long as he is indoor-only and well cared for. Right now he is in foster care with a friend of ours, and has potential placement as a solo cat.