Blood Type A: Careful and hardworking but shy; internally nervous and worried about others.
Blood Type B: Fun-loving and charismatic, but unpredictable and can be rude, selfish, and/or lazy.
Blood Type O: Sociable (can be over-sociable), optimistic, and a natural leader.
Blood Type AB: Serious, smart, and able, but aloof and eccentric.
When the four bloodtypes are in the same room, the quiet TYPE A would be near the wall so as not to attract attention, self-centered TYPE B would naturally go to the center of the room, TYPE AB would be daydreaming in a corner, and TYPE O would be walking around the whole room socializing.