On Jun 5, 4:36 pm, wrote:
Once I chased them up the alley with a broom. My cat was behind
me. He got so upset he jumped on my ankle and scratched me and then
hissed at me. I guess he didnt want them to leave.

On it's face that's what it would seem, but I think it's somewhat
more complex than that.

I had a similar problem when I was doing something outside and
my cat Mama was with me.

A woman came by with her female cat following her.
Both were nice enough, however Mama didn't like the other female
cat and kept her distance while eying her intently.
The woman tried to pet Mama to calm her fear, and I warned her not to.
Sure enough Mama lashed out and scratched the woman.

You see in Mama's eyes, she's looking at the other female cat, and
the
hand reaching down to pet her is an extension of that cat.
That hand will be attacked as if the other cat itself were too close.

It doesn't matter whose hand it is, it could have just as well been
mine.