UPDATE: MoMo’s new favorite spot is Lola’s dog bed, which provides perfect camouflage. (Fortunately, Lola has other beds and favorite spots, so she has conceded this one.)
Three months out, MoMo, Phoebe (my other rescue cat), and Lola have all developed a state of mutual tolerance, which gets better each week. Each one has his/her preferred spot in the house, and Phoebe and MoMo have started making friends, touching noses and doing head bumps.
MoMo’s various ailments have also gotten better — his eye is almost completely cleared up, his coat looks better, and his personality (testy and territorial for the first 6 weeks) has improved to the point where all 3 pets can be left alone without fear of squabbles.
Thanks again for helping me to see what a wonderful addition MoMo would be. You were right: the stress of being in the shelter for so long had definitely soured his outlook on life. Once in new surroundings, with his own “space,” quiet companionship, and lots of snuggles, he came into himself again.