I have a question that I'm hoping someone knows the answer to!  I
apologize in advance for the long-winded explanation.

I have two cats - one is a 5 year old domestic medium hair, and the
other is a 9 month old Ragdoll.  They get along great, and the younger
arrival has definitely improved the life of the older one.

There is one thing that I can't figure out, however.  Whenever my
fiance or I leave our home, the older cat will run over to the younger
one and bite him on the back of the neck.  He'll even come running out
of his cat tree to do it.  He doesn't seem to be mounting him, he just
sort of comes at him from behind on an angle.  He sort of holds him
there for a few minutes before letting go (or the younger one finally
decides to roll over to get him off).  It doesn't seem to be hurting
the Ragdoll, who seems to just lay there quietly while he does it.  Its
like clockwork - we can shut the door, and reopen it 15 seconds later
to see the older cat holding down the younger one.

This sometimes happens at other times, usually at night when we're in
the bedroom and they're in another room.  We'll hear the usual "war
cry" that the older one makes before doing this strange action.

We can't figure out why he's doing this!  Its almost like he's trying
to preven the younger one from joining us out the door?  Has anyone
else seen this strange behaviour?

Thanks,
J