The first broad hint as to this occurred when Fiona and her cat Beaumont showed up in May 1991. The part of me that first started to suspect that Elly had no immediate use for cats was her panicky caterwauling about how the cat PROWLED HER KITCHEN!!! because everyone knows that cats are sneaky and mean and destructive and evil and they suck the breath out of babies and yap-yap-yap.
The other broadish hint is when Liz brought Shiimsaa; while Liz's main complaint was that the poor dumb animal's need to be affectionate led her to step on keyboards and erase e-mails, Elly was once again yowling about the destructive monster PROWLING HER KITCHEN!!!!!
This is sort of a problem because one of the odder habits that cats have is that they can sense when people are uncomfortable and unknowingly worsen the problem by getting affectionate. The pussycats of the world have no idea that they live in a world where angry, panicky, ugly yappity-yap about their being fauna of Mordor isn't called out as being errant bullshit and thus don't and can't realize that their attempt to ingratiate themselves with what they seem to see as a larger cat simply makes things worse for them. This means that the more Liz's cat tries to make the loud human love her, the more BEEFING ABOUT PROWLING HER KITCHEN!!!!!!!! Elly is going to make.