When we adopted a pair of cats, brother and sister, we renamed them to Simon and River, in honor of the Tams.
It occurred to me that this isn't the first time I've had a male cat named Simon. Long ago, a friend picked up a stray cat, a girl, and this being 1982 or 1983, I suggested the name Rio, after the album of that name by Duran Duran. Turned out she was pregnant, and had five boy kittens. So there wasn't really any choice: the kittens got named Simon, Nick, John, Roger, and Andy. It seemed quite fitting.
Of course I can't just call the current Simon "Simon"; I have to elaborate. One of the names I've given him, due to what a little upstart troublemaker he can be, is Simón Bolívar, which then gets mutated to Señor Bolívar.
So calling him by a Spanish language name, I naturally considered the idea of calling River by her Spanish equivalent, which is, of course, Río. Which would bring me full circle, to having a pair of related cats with the same names as another pair of related cats.
As insignificant a set of coincidences as can possibly be imagined, but it makes me wonder. The link between the names Simon and River existed before Firefly; is there the slightest chance that Joss did that on purpose?