I am re-reading all the books from 1 to 7, and I noticed something that I haven't really noticed before. It may be a translation error, but at the start of the book, Voldemort refers to his snake like he did in the previous books, Nagaine. Later, after Harry kisses Ginny as his birthday gift, Voldemort refers to his snake as "Naginny". I am reading in a translated language, so it might just be the interpretor forgetting he already translated the snake's name. I don't know if the same thing happens in the english version (I doubt it does), but it's quite weird. Also let's not forget that Dumbledore claims in Book 6 that Nagine is possibly the only thing he loves if he is capable of loving, which is rises my suspicion meter even higher.