I am looking for possible ways in which a vampire could obtain blood to feed in an modern urban fantasy setting explicitly without harming humans or other sapient beings. Parameters for this question are as follows:
- "Harming" as defined here includes voluntary victims. No vampire wannabes who want to be bitten, a lover letting them drink their blood, etc.
- The setting is essentially the present day. Stereotypical masquerade rules apply. Society at large is unaware of the vampires and while the government does know it doesn't give them blood wellfare, small numbers of individuals are allowed to know at a personal level (e.g., humans who know vampires personally). Vampires live alone or in small groups.
- The vampires aren't fantastically wealthy. They are more or less average people, so they can't just throw money at the problem until it goes away and bribe anyone who looks at them funny.
- The vampires in question are utterly biological. No walking corpses, no supernatural “life force” they consume to explain why they are drinking blood, no immortality (their lifespans are the same as humans), no "mind whammy to forget feeding", no nothing. Basically just a humanoid species that drinks blood. Anything that goes for a real vampire bat goes here. Mentally they are basically human and try to pass as such, hence them looking for options for blood that do not involve harming others.
- How much blood is needed each night is not that much of an issue. I realize that blood is probably the least nutritious substance in the human body by weight (being 80-90% water), and that it is probably not possible to feed a warm-blooded human-sized organism with a large, nutrient-hungry brain on blood alone, given that vampire bats barely manage to avoid starving to death most nights. I am more looking for possible avenues that vampires could get blood rather than whether or not a particular source is efficient or the viability of a stereotypical urban fantasy masquerade. However, I realize by this definition they could feed on lab mice and that would satisfy the criteria. If metabolic parameters are absolutely necessary, let's go with...low enough that they can exist but high enough that they can't just feed once a year like a python and the whole thing is a non-issue.
- There are no limits to where the blood can come from. Animal blood, human blood, blood from still-living organisms, stored blood. Anything that can be used to feed a real blood-drinking animal (vampire bat, biting insect, lamprey) is acceptable. The only caveat is that it can’t be taken from live human donors. So no “draining the innocent in their sleep” or “only drinking the blood of criminals”, and so forth.
- Crime is to be generally avoided if possible. The vampires are trying to fit in to society, murder is out, something like "rob a bank and use the money to buy blood" is out, but discreet stuff like drinking someone else's livestock as long as you don't get caught is okay. They basically just want quiet lives and would prefer to do things legally if at all possible.
Although preserved blood in blood bags fits the parameters, I think swiping blood bags from a hospital might be right out. Mostly because getting access to said blood bags in the first place isn't likely to be easy and hospitals tend to notice these kinds of things if they are done often enough. Additionally, doing so greatly increases the risk of getting a bloodborne pathogen. Plus I hear there are lots of preservatives in it to keep red blood cells from dying.
One option I have often heard suggested in these stories is eating extremely rare steaks and other meats. However, it turns out most of the “blood” in rare meat is myoglobin, and that the blood is drained from the animal at the slaughterhouse before it is butchered and sold. The myoglobin is in the meat cells so it can’t easily be gotten rid of. Would myoglobin be digestible to a blood-drinking organism like a vampire bat?
Another option I have heard of is that milk is produced from the body’s blood. However, I have also read a lot that says that it isn’t, and at best you can say it’s only metaphorically true because it’s made from the same nutrients that the bloodstream carries to all parts of the body. But by that logic all the flesh and secretions in the body have to be considered “blood”. You can have blood in milk, but it usually means the animal is sick or hurt.
The best options I can think of are:
- Preying on wildlife like deer or raccoons
- Doing what real vampire bats do and sneak into livestock farms in the night to lap up blood from cuts on their ankles. Zoos are another option, but those animals are supervised for unusual wounds pretty closely by the keepers.
- Blood from slaughterhouses, though I don't know how easy it actually is to get blood from them despite the prevalence of vampires getting blood from slaughterhouses in fiction
- Internet? Dark web?
However I am not sure how well these work.