I am new to this grouop and happy to find some more information on cats.
However, I have not researched yet on my topic as my two cats keep me busy
and I need fast advise cause I don't want anything to happen or create two
life time long enemies.

we just adopted a one year old cat from Humane Society. We always wanted to
have someone for our older cat (6year old) to play with. as she is a very
active cat.

The new cat wants to play with the older cat and constantly tries to get
close to her but the older one keeps on hissing at her.

any one has some suggestion how they can become friends or is it like human
being that they don't go along with certain people.

I also would like to know if cats normally share one cat litter or do they
have to have their own.