Animals weren't something Ryuuko had much a chance to interact with, as they often frightened her, so she never did get much a chance to interact with them without bouncing back and running to hide. However, something about something furry and friendly would attract her curiousity. This furry something would come in the form of a black and white kitten that someone had given Nui out of a token of good will.
The kitten, being as curious as kittens often are, padded around, which prompted Ryuuko to hide for a little bit before curiousity took over. "Kittens are for petting, Ryuu." Nui explained, the explanation prompting a curious but confused expressing with the question of, "Petting?" Prior to setting her free, neither Nui nor I had a pet and Ryuuko's past recollections don't have animals in them but she did know what petting was and petting was a show of affection. While she knew that tidbit, she didn't know what pets were and not knowing piqued her curiosuity, leading her to ask, "What is kitten?"
"You mean 'What is a kitten?' Well, a kitten is a baby cat.
"Huh, what's cat?"
"A cat is a bigger version of a kitten."
"Eat?"
"No, there are some things you don't eat and cats are one of those things you don't eat."
"Okay."
"See? Kittens are for petting, not eating."
"Meela."
"Oh, you want to name her-?"
"Meela."
"Meela" seemed to be her name for Nui's pet, although we weren't sure as to what the name meant to her, however, a name to Ryuuko was what other people are called and she had quietly acknowledged the fact that she was given a name, so, to her, a name for the kitten was thus. We didn't know where she had heard the name "Meela", then again, she probably heard a similar name and heard it as she articulated it.
She was happy and quite fascinated with this little kitten, even opted to follow her around, reaching out to pet her every few moments. Meela was just as curious about her and reciprocated the action as only a kitten could. Ryuuko was taken aback by the action but responded by petting her again. It was odd, yet humorous, as we never seen her react remotely friendly, curious, or playful with an animal, however, she was doing just that, with something that didn't frighten her.
It's nice that she found something that didn't frighten her.