This is an idea I came up with, and haven't done anything with it.
There's a bridge in a small town where a cat sits. Whenever someone crosses the bridge, the cat will walk along side them until they step off the bridge. If more then one person is crossing the bridge, the cat will do it's best to walk beside all of them, darting back and forth.
There's a young girl that crosses the bridge every day, and she has befriended the cat. She'll stop and sit on the bridge and give the cat something to eat and just generally talk to the cat. She has affectionately named the cat Bridges.
One day at home, she's sitting with her mother, father, and younger brother at the dinner table, and she starts talking about the cat. The dad says it's just some stray that stays there because people keep dropping it scraps. He even remembers the cat from when he was a boy. He pauses and realizes it couldn't be the same cat as it would be very old. He dismisses and just keeps eating. The young girl thinks that the cat is there to make sure no one gets lost, that they go the right direction, and her younger brother laughs at her saying, it's a bridge, there's only two ways you can go.
One day, the young brother decides to play a prank on his sister. He goes to the bridge and kidnaps the cat. When the young girl gets to the bridge, she looks around but doesn't see the cat. She waits a while and then goes on her way.
What happens is that it turns out the cat is a guardian between two worlds. His job is to make sure people from each world don't cross over into the opposite world. The simple act of him walking alongside someone was enough to make sure they didn't stray off the path into the other world. With the cat gone, the young girl walks off into the other world.
After that, I've got nothing really. No real plans for what kind of world it is or anything. The most I can get written is a few paragraphs, and none of that is any good. I'm not much of a writer. I tend to come up with pretty good ideas, just can't get the details down.
interesting story. there is a lot of play here. as to what the other world is. could be like earth two. where two of the same person can make a paradox and destroy both worlds and the cat is the gate keeper or watcher. or the other world could be in the past or future. or better yet the cat could be the guardian to the gates of hell. so grab one of these tasty tidbits and run with it. have fun.