Thanks for your reply love4himies. They both had their appointments about 2 weeks ago, only resulting in a rescheduled spay. We have yet to have good timing when we try to bring Gracie in when she isn't in heat. Other than the usual talk of spaying Gracie, their appointment went without a hitch (although that was a few days before we found Ollie).
Gracie we got from a co-worker, whose daughter was a little too rough with their kittens (they had two sisters). Charlie was actually a stray that was brought into the vet where I worked at the time to be euthanized, however the vets and myself fell in love with him; we therefore took the money given to us from the pound and used it towards his needles and neuter.
The fights have now escalated to everytime Gracie lays eyes on Charlie; food isn't a factor. Charlie will be sound asleep and she sneaks up and attacks him. It is almost as if she's possessed... not the little girl we have known this whole time.