merry meet,the only few i know are blood brothers, swaping blood to bring another into your family or tradition ,and a animal familiar spiritguide sating where you let your familiar drink your blood from your birthmark to bind them to you, like for like.The other is blood letting ritual sacrifice for fertlizeing land all are gross and id never do them their straight forward as written lol blessings )O(
I hope you are not thinking about doing some "vampire stuff" lol But as previously stated there are blood pact rituals and fertility rituals that require blood but I have never heard of a practical use of drinking blood. Also be aware of various microscopic nasties that can be present in blood. You run the risk of contracting a number of diseases and disorders. I advise against it.