I'm reading from the Ultimate Unofficial Guide to the Mysteries of Harry Potter, pg. 200:
Not only is Lupin's last name derived from the Latin word for wolf, but, according to the legend of Romulus and Remus, Remus was murdered by his brother (or by his brother's followers)... There is a lot more to learn about Lupin (like what the "J" in R.J. Lupin stands for)
Well, I read in a chat that (I think) the "J" stands for James, but it was some "boring" name, and Rowling said it wasn't major for the story.
But is it possible someone Lupin trusts (a "brother") will be the one to kill him?