There exist abilities that are specifically tuned to certain individuals or clans. One of these strange abilities is known as blood-bending, which is the power to turn an individual's blood against them. Blood bending can be used in several ways to fulfil various purposes. A user can manipulate an individual's blood in order to control their movements and actions from a distance. It can be used to draw a victims blood through the pores in their skin in order to manufacture physical manifestations of objects instantaneously. This can be specifically used to form weapons in battle, such as swords, sickles, projectiles, etc. Finally, a user can draw out a person's blood and absorb it into their own supply, healing wounds and restoring their life force.

While blood bending is a powerful technique, its effectiveness can vary between the different blood types. Certain blood types are barely malleable, and would remain mostly unaffected by a skilled blood bender. Others are moderately effective, with a user being able to control their movements to some extent, and create brittle and easily shatterable weapons from them. Some can be very affected by a blood bender, who will be able to create firm and powerful weapons from their blood, use their blood to heal themselves, and take full control of the victim's body.

I need to find some specific distinction between blood types that would justify making some more receptive to being controlled by another's influence than others. What attribute would I be able to use for this power?

  • $\begingroup$ nothing, blood does not interact with brain tissue directly unless something has gone horribly wrong. $\endgroup$
    – John
    Commented Feb 6, 2021 at 16:01
  • $\begingroup$ You want to take a look at this:tofugu.com/japan/japanese-blood-type The Japanese most definitely do not share John's opinion. en.wikipedia.org/wiki/Blood_type_personality_theory .. as this question is in context of people with magical "Blood bending" abilities, I think we can forgive the iffy science of blood-personality linkage? $\endgroup$
    – PcMan
    Commented Feb 6, 2021 at 16:42

2 Answers 2


You just listed them: different blood types express different surface proteins in their blood cells. These surface proteins act as antennas for the magic. Different figures of merit for different antennas justify why certain blood types are more receptive than others. Think of radio without antenna.


Compatibility Issues:

I would propose that the degrees of compatibility with the caster would determine what effects your magic would have. Let's give a little tutorial on blood types to explain.

Blood type is determined by the presence of antigens on the surface of red cells. There are LOTS more antigens, but these are important because they are ones we share with intestinal bacteria. If you have the antigen on your OWN cells, you don't develop antibodies to it. But if you DON'T have the antigen on your cells, your exposure to the intestinal bacteria means you are virtually guaranteed to have antibodies against it.

The antigens are A and B. RH (the +/-) is a factor, but only if you are exposed to it during transfusion or pregnancy. A, B and O are all alleles, but O is recessive, so you can have O people who are O/O, A people who are A/O or A/A, B's with B/O or B/B, and AB people are always A/B. O people have neither A nor B, while A people have A, B have B, and AB people have both A and B. The relative percentile for types are given below on the chart.

So in GIVING blood, O people can give their blood to anyone - their blood doesn't have the antigens, so the donor won't have antibodies against the donor cells. Conversely, AB people can GET blood from anyone, but ONLY give blood to other AB people. O people would be used for healing, while AB people would be very restricted.

For plasma (the liquid part of the blood that contains antibodies) the rules are reversed. AB people have NO A or B antibodies, so they can give (antibody-free) plasma to anyone. O people can give plasma only to other O people because the have antibodies to BOTH A and B.

So your benders would have different powers depending on their compatibility. Lets say, for example, healing is based on red cells. AB benders can take health from anyone, because they can take red cells from anyone. They could only HEAL other AB people, if healing others was a thing. O benders can only take health from other O people, but could GIVE health to anyone, since their blood is universally compatible. A and B benders would find themselves somewhere in the middle, unsure of who they could or couldn't heal/drain.

Conversely, let's say weapons are made from solidified plasma. The O bender can take plasma from ANYONE, so they are always able to make good weapons. AB benders would find it hard to EVER make good weapons, OR they would have to make weapons from their own bodies, then drain health from others to compensate. Again, A and B benders would find themselves somewhere in the uncertain middle.

Thus logically, every bender would need to know their "victim" type for best effect, but O's and AB's would have the most consistent results with their universal compatibilities/incompatibilities. Different blood types would give rise to different kinds of benders with differing strengths and weaknesses. A's and O's would generally be powerful due to the frequency of compatible blood and plasma. B's the least. O's and AB's would be more specialized and consistent (O's most powerful due to the higher frequency of O blood).

The Rh factor would be a complicating detail. Rh positive people can use Rh negative blood, because almost no one naturally develops antibodies to Rh - until exposed. While Rh negative people are rarer, once exposed to Rh positive blood, they develop antibodies to it. Thus Rh negatives exposed to bender healing from an Rh positive bender would become incompatible to Rh positive benders. Rh negative benders would be at a severe disadvantage, because once they were exposed to Rh positive blood, they could no longer take from any more Rh positive people. Rh negative benders would thus be very specialized indeed (only able to draw on Rh negatives), while Rh negative "normals" would become immune to or worthless for Rh positive benders after an initial exposure (at least for tool/plasma applications). AB negative people would be almost immune to magic - but are also the rarest type, less than 1%.

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