We have two seven year-old brothers--Buck (long black hair) and Curly
(Siamese in appearance).  They have always lived together and gotten
along well, with only minor brief hissing incidents occassionally.
Most of the time they were good pals, spending lots of time sitting
next to each other.  They were neutered as kittens.

Yesterday they had a fight, no injuries as far as I can tell.
Apparently a chair fell over on the porch.  Buck ran.  Curly chased
him into a corner and kept hissing at him.  A minute later Curly
chased Buck around the house, both of them hissing.  Finally, Buck
fought back.  They snarled and hissed face to face, and then it was
Buck who chased Curly behind a couch.

Now almost 24 hours later, Curly is still hissing and moaning and
behaving threateningly toward us as well as Buck.  When Buck has been
away, Curly has come out once or twice, and early this morning even
let one of us pet him, though he hissed at Buck when Buck came into
the room.  For his part, Buck does not seem upset except in reaction
to Curly.  However, Buck has chased him a few more times and has
seemed to corner him and hiss at him.  I don't know if it has been
solely in reaction to Curly's behavior or aggression of his own.

We are at a loss as to why they are fighting like this now, after all
this time together.  We don't understand what is going on.  We don't
know if they are a danger to each other when left alone.  And we
certainly don't know a way to resolve the problem.  Can anyone here
provide some insight and advice?

Thanks,

Jeff