Bloodplay is hard to research, possibly since blood = AIDS, these days.

You should be able to view this entry I made quite a while earlier discussing my own search for bloodplay resources. There's one semi-useful site discussed and a bit of personal experience from xandria.

If this is for Alec and Richard, it reminds me that I need to write... knifeplay, as opposed to bloodplay, with them. Somehow, it's more about Richard's swords than Alec's blood for Alec in my head, even when the two meet.