Cat Hostile to Friend After Neuter. Why?

Hi All,
I'm having more cat trouble lately. :-) Fortunately, most of it has
turned out well. Anyway, Some weeks ago we took in a young feral cat,
Froggy. He settled in well and has begun responding to affection and
allowing our touch. :-) But from the moment he joined us, he and my
neutered male, Squidly, have been fast friends. I mean, totally
inseparable. Always playing or sleeping together in a tangle. It's
wonderful to watch. Squidly grooms the little one just like a mother and
they roll around on the floor for hours playing.Here they a

http://www.wtv-zone.com/nutfish/cats/squidfrog1.jpg

Anyway, yesterday came Froggy's day for neutering. We brought the
little guy home last night and let him out. Squidly HISSED at him! Just
refused to have anything to do with him. In fact he actually seems to be
afraid of him a little. He hisses and growls whenever the young one gets
near him. It's heartbreaking, because Froggy's in a little pain and
groggy, and he wants to sleep with his buddy and be comforted. You can
actually see the confusion on his face. It's the weirdest thing.

We thought it was maybe the strange smells from the vet, but here it
is the next day and still he hisses and snarls whenever Froggy tries to
approach him. I realize that time is probably the only cure for this, if
any, but I'm very curious about why this happened and if there's
anything I can do to help restore a lovely friendship. Thanks for any
insights. :-)

Robyn
--
To avoid grizzlies, the Alaska Department of Fish & Game advises hikers
to wear noisy little bells on clothes and carry pepper spray. Also watch
for signs of activity: Black bear scat is smaller and contains berries;
grizzly scat has little bells in it and smells like pepper.