I have a new but hidden cat
No, not the cat named Lily that I thought I was going to adopt. Some friends of my husband had to reduce the number of their cat at least until they can move out of the decrepit mobile home to another location. So he agreed to adopt "Blackie" a adult neutered black male cat with one eye. The description I got was that he spent most of his time outside, didn't answer to his name and would eat anything.
My husband brought him home Monday afternoon. He had set up the bathroom upstairs for the cat with food, water and a litter box. My plan was that we would leave him in there for a few days, let my cat interact through the door and take it from there. My cat went upstairs but seemed unaware there was another cat in the house.
Yesterday we had an appointment in town. Without telling me my husband left the door to the bathroom where Blackie was living open. When we got home, Blackie was no where to be found. We still have not seen or heard from Blackie. We've looked all over the house and haven't seen the cat. Although we have a cat door to the outside, Blackie doesn't know where it is or how to use it.
Upstairs, Blackie only had access to the bathroom, the hallway and my husband's office. The way down the stairs is completely open, but Blackie was very frightened, in a new house with new people and the smell of an unknown cat all around. My cat has not reacted at all, so he's not giving us any clues to where Blackie can be.
I don't think Blackie has made it down the stairs. I think he found some place upstairs to hide that my husband hasn't found.
My only theory at this point is that Blackie crawled up inside the recliner in my husband's office as a place to hide. But we can't get to the back right now and even if we could we wouldn't be able to see all the crevices a cat could hide - we know this from past experiences.
We're still putting fresh food and water out and my husband can check the litter box to see if it's been used - but my cat can now get in to use/mark it so that may not help.
At this point, I am not sure what to do to find Blackie and try to make him more comfortable here.
= new reply since forum marked as read
I also feel bad since this is supposed to be a temporary adoption. The owners are hoping they can find a place to live where all their cats will be welcome. Also, where they are living now is far away from a bus stop and they can no longer walk the distance especially with a Florida summer coming - this past winter with the rain and cold was bad enough. So they are looking for somewhere in town close to transportation and shopping for really cheap.
But I know how a new cat in the house can hide. Before I married my husband he adopted a gray long haired cat off the side of some road. He put the cat in a spare bedroom - didn't see it again for a month. He put food and water in, it disappeared. He provided a litter box which was used regularly. But the cat never showed itself. Finally one day it ventured out and started eating in the kitchen with the other cat of the house, but would retreat back to his bedroom most of the rest of the time.
The cat was never friendly, never let anyone pet it. Eventually he would ask to be let out and back in the house door and seemed to have settled in. Unfortunately he liked exploring cars. He climbed into a friend's car and may have fallen asleep in the back seat. They drove to Panama City to the beach and when they opened the car door, the cat took off - that was the first they knew he was in the car. We never found him again. I hope he found a good home, but he was self sufficient before my husband took him home so I guess he was able to take care of himself. 
All kittehs like noms.
I'm sure he'll be okay.
He'll come around.
Every kittums like a nip toy. 
These are infused with catnip. I have two of them and my three cats play on them all day long. 
Glad you have seen Blackie around! I hope he comes out and joins the rest of the family soon!
