Old cat new cat

Question
I had two 5 year old cats (litter mates) until one died about 6 months ago.  
The remaining cat seemed lonely, even after the adjustment period, so a
week ago I adopted an 8 month old.  I am keeping them separate most of the
time, unless I am at home and paying attention when I let the new cat out of
her room.  Unfortunately, my old cat continues to hide under the bed
whenever the new cat is around.  She has tried to come out several times but
the new cat chases her back under the bed.  They have fought a couple of
times, with hissing and throwing paws.  Each fight has ended with me
grabbing the new kitty and putting her in her room and my old cat under the
bed.  Do you have any suggestions?  I do not want the new cat to completely
dominate my old one if at all possible.  

Answer
Christina,

There are two rules I have about cat inter-relationships: (1) No human interference, it is almost always counter-productive and  (2) We do not understand how cats work out their relationships with one another.

So, what I think you should do is to leave the the two cats to work it out.  Do not separate them.  The more you intervene the longer it will take for things to resolve.

We often ascribe human motives and emotions to things cats do.  We are not looking at it from the cat perspective.  If they are playing chase, even if it ends up in a "fight", that is a good thing. You need to ignore the noise and even loose fur.  Cats will rarely really hurt each other.  You must remember that cat skin is very tough.

Whoever ends up as the dominate cat ends up as the dominate cat, it is up to the cats to figure this out.

So, were I you, I would leave them be and no longer separate them whether you are home or not.  Give them a few weeks to come to terms.  Ignore any noise or "fighting".

In the longer term they will work out how they want to relate to each other and go on from there.

If you have more than one litter pan for the two of them, that will keep tensions down.  Lavishing extra treats and attention on your older cat would be a good thing. If he wants to stay under the bed, for now, you need to just bear with him.

It may take a few days or weeks for them to come to terms with each other, so you will need much patience.

Please keep me posted on their progress.

Best regards... Norm.