Lupin | Snape
Because I was brought here from a point in time that was mere minutes before my death. The only new memories I could be given would therefore be of my death and I've already read that part of the books. It was unpleasant.
It could also make the full moon much, much worse for them. But as the effects on them are unknown, if they wish to try it, I am certainly amenable to making the potion for them.