Why do cats purr?

[Bumfluff]

Why was she waking you up?

My cat knows that if he wakes us up during the night he's going out. Doesn't matter what else he wants, or how cute he tries to act, the only place I'm taking him to is the front door.
It took a couple of months but it did reduce the frequency of the nocturnal requests

Not sure why she does it, she was ok for a few weeks then it kicked in, she just wants to be out most of the time. I dont have a cat flap though only reason I dont want them bringing dead stuff in. I think she is a bit wild / ferial, its the most challenging cat Ive ever come across, if anyone comes round the house and the cat is in I have to tell them to keep away from her as she is so unpredictable and dangerous.

The wierd thing is the other cat is this cats sister, the other cat is totally different personality, sleeps pretty much all the time and only tries to get in the bedroom when it hears the alarm going off in the morning.