Plant dad and clever sculptor Willy informed me this weekend that the plant is a Hoya. This news inspires such possible plant names as Latoya, Gioia, and Inigo Montoya. But let's not pretend; obviously the plant's name is now Latoya.
I was glad to discover upon reading this page that Latoya's success could be at least partially attributed to my placement of her in my north(east)-facing bathroom window. I've also been unwittingly treating her as she likes to be treated, as the page says Hoyas "resent pampering," and I pretty much leave her to her own devices.
Go Latoya, go!