Cat distraction

This is Renee, my foster cat. I am hosting her weekdays, and she spends weekends at the animal shelter, hoping to be adopted for real. She is very timid, and spends as much time as possible hiding under furniture. She lives in my spare bedroom, and I bring her out for supervised "playtime" with Daisy in the evenings. Daisy is very well-behaved, and just seems to want to make friends. However, Renee has never lived with another cat in her 4 years, and just growls and hisses whenever Daisy so much as looks in her direction from a distance of less than ten feet. That's why this moment this evening was so momentous:

Unfortunately, it was short-lived. Now Renee is hiding under a dining room chair across the room and Daisy is still in her spot on the couch and they are having a staring contest. But at least there's no hissing so far.