My Cat Sister, Agnus

This is my cat sister, Agnes. She is much smaller than I am, maybe half my size, but I'm scared of her. She hisses and jumps at me and she can double in size (mama #2 calls it "fluffing")!
Anyway, Agnes likes to explore. When I was still a pup, I watched in wonder as she would leap over the fence into the neighbor's yard and into the alley behind the yard. I'd carefully look through the fence to see what she does and why she leaves the yard. She does......nothing! She sits, she watches, she sleeps. Sometimes, she hunts. How boring!
She travels, too. I've watched her walk across the street and go down the next alley. Sometimes she's gone all day. When she comes back, she carries many different, strange and exciting smells.I think she travels a long way; maybe as far as I go on forced marches.
Her mom cat lives with us too; her name is Millie the evil cat. 'Nuff said.
The really strange thing about Agnes is, she likes to come with us on forced marches (so does the evil cat, but she's so fat, she can't waddle very far). Mama #2 always looks for Agnes before she takes us out to march. If she sees her, she puts her in the house.
Agnes is very good at hiding, waiting and watching for us to leave on our marches. When she sees us, she dashes out and joins us. Sometimes Mama #2  will let her come with us for a couple of blocks, then she'll march us all back home and make Agnes go into the house so she won't follow us any more.
When Agnes marches, she gets to run free. Mama #2 never puts anything around her neck to drag her along. She runs from behind us to in front of us. She jumps fences and runs through strange yards. She likes to march on top of one stone fence. She spies on the dogs that scream (bark) as we walk by their houses.
If I could explore yards and go at my own pace, I might like marches too. I'd really like it if I only had to march three blocks!
How do I convince Mama #2 that I'm really a cat?