Aggressive Female, Lazy Male?

I have three kitties: Luke (male, fixed, 8 months), Leia (female, fixed, 7 months), and Baby (female, 6 months). While trying to breed Baby, we brought in a male for her (Mr. Peanut). I thought it would be an all-out war between Mr. Peanut and Luke, but it was entirely the opposite! Luke was laying down and barely raised his head as Peanut sniffed him. Leia, on the other hand, was stalking Peanut, pouncing him, and never took her eyes off of him. There were no fights, to everyone's amazement (breeding didn't take place either, even though we left Peanut and Baby alone without the others on the back porch overnight).
I always thought males were aggressive with other males. Could it be that since Luke is fixed, he doesn't feel the need to be aggressive? What about Leia? Why would she be so territorial?
I adopted them all at early ages. Luke was rescued from a shelter at 2 months of age (when I adopted him). Leia and Baby were from the same mother, one litter apart (Leia was 2 months, Baby was 1 month when I got them).

[LindaTX]

I'm curious....if you expected an "all-out war" between the male cats, why would you put your cats in that position?  And then leave them alone with Mr Peanut since they were not aquainted with him. You said Leia pounced on him and then you left them alone in your screened-in porch where they "live" according to your other post.  I'm also just curious why you are wanting Baby to have a litter of kittens?  Especially since they are "living" in such close quarters.  The answer to your question about Luke is he is not aggressive toward Mr P. because he has been neutered.  As far as Leia being territorial...maybe she feels stressed in the close quarters and just "needs her space."

[opus88]

I agree with Linda, why on earth would you want to breed a BABY at 6 months old???
she isn't near old enough to become a mommy, this can lead to many health problems for her and kittens too!!
please reconsider your actions for the poor girls sake....she is barely a kitten herself.

[nancyjac]

First of all, kittens one month apart in age can't possibly have the same mother.  The gestation period is about 9 week so even if the mother got pregnant again the day she delivered (which isn't going to happen), the litters would be over 2 months apart in age.

Secondly, kittens (under a year) who get pregnant most often have difficult pregnancies and stillborn or deformed litters.