Depression in Indoor Cat

[Calliope85]

I have a very sweet male cat who is semi-feral.  He has really come a long way in terms of being comfortable with us, but prefers to be outside.  However, he has a severe flea allergy and really needs to be indoor always.  I used to let him go hang out on the back patio for a couple hours a day, but he would always get reinfested.  He has been inside now for about 2 months straight and is getting very depressed.  I actually brought in his sister as well because she has the same flea allergy, and she is completely feral(never have and never will be able to touch her), yet she is happy as a clam.  But this poor guy just constantly cries and asks to go outside.  If any of your have dealt with depression in your cats and have any tips I would be grateful for any suggestions.

[tropicana]

get him stoned on high quantities of quality cat nip? 

seriously.

and when he is "high," spend LOTS of time petting and grooming him, feed him special treats, and introduce him to some new indoor sensations -- perhaps a desk fountain for water play and entertainment. 

does he have any inside playmates? another cat with whom his personality clicks? or a mellow cat-loving dog?

can you take the cat out on leash walks? possibly?

[starrlamia]

play with him, offer him enrichment. You could also invest in flea stuff for cats...