Type AB's are the split personalities of the blood groups. They can be both outgoing and shy, confident and timid. While responsible, too much responsibility will cause a problem. They are trustworthy and like to help others.
People with blood type AB are hard to categorize. They can have characteristics on both ends of the spectrum at the same time. For instance, they are both shy and outgoing. They easily switch from one opposite to another. AB people are trustworthy and responsible, but can't handle it when too much is asked of them. They don't mind doing favors or helping out, as long as its on their own conditions. People with this blood type are interested in art and metaphysics.
AB is considered the worst blood type. In predictability-loving Japan, they're loose cannons. They also like to set their own conditions and reserve the right to drop out when things don't meet their expectations. They're known to be sensitive and considerate—at times—but it just isn't enough to balance out the flaws in this blood type. For a while, some companies tried dividing their employees into work groups based on blood type, and no one wanted to work with the AB group. Anime villains are likely to be type AB.
Uchiha Sasuke, Hongo Yui, Tomo, Trowa Barton, Kenshin