Kaylee hadn’t really thought much on how they had fit in. It must have been hard for them, to come to Serenity as passengers, then having to stay and learn to be accepted. Kaylee remembered the feeling all too well, her first days on Serenity very strange as she learned she was the reason Bester got fired, as she struggled to learn everything about a Firefly, fearing the Capt’n would fire her too if she messed up. Gradually though she, as had Simon and River, learned all about the crew, learned what to say and what not to say, and finally became an accepted part of the family.
-- The Dr. Tam Journals - Part 2 - The Train Job by cbsteve