I'm sorry that your question wasn't answered in a timely manner. I'm going to address both petting and prey aggression as I believe that these are both present in this cat. You'll see redundancy in the discussions but read through both and you'll get a good idea of what's going on here and how it might be addressed.
Some cats have the disconcerting habit of accepting their owner's attention only to respond by biting when they have had enough. In general, these cats seem to enjoy social attention. They may actually seek attention by crying, rubbing against people, or jumping into their laps. However, they seem to have a certain threshold for the amount of physical attention they will tolerate. When they have no more tolerance for stroking, they bite and may run off. The observant owner may be able to tell when the bite is about to occur as the pet usually will show typical behaviors that may include fidgeting, tail twitching, tenseness, leaning away, ears flattened against the head, retraction of the lips, and hissing. The prognosis for correcting this type of behavior is fair to guarded, depending on the duration of the behavior, his threshold for physical interaction, and your patience. Young children are at a greater risk, as they don't "read" the postural signs that a bite is imminent. The crux of treatment is to identify the threshold of tolerance for the cat and to gradually condition it to accept more stroking while avoiding the risks of attack. To do this, you must first determine how long the cat can always be stroked before it attacks. Retraining sessions only take place when the cat is in the mood for affection. Petting should then take place for a short period of time and stop before the threshold is reached. The cat can then be given a food treat and placed on the floor before it shows any evidence of nervousness or aggression. The cat must not be held or confined in any way. It is better for it to jump down on its own rather than become aggressive. The sessions can gradually be lengthened as the cat learns to tolerate longer and longer stroking sessions in anticipation of a food reward (desensitization and counterconditioning). The owner should have frequent petting sessions with the pet in the lap or next to you on the sofa. Punishment (physical or yelling) should be avoided. This problem is avoided by early socialization (prior to 7 weeks of age), grooming and frequent handling of the young kitten - a moot point at this time.
This is a dangerous form of aggression and you must decide if the potential risks to your family are acceptable while you attempt to address his behavior. Cat bite wounds have sent too many of my owners to the ER. Please be very careful around him. Note how his level of arousal remained high even after his initial aggression.
The clues for predatory aggression are the caretaker being bitten when a body part moves. Predation is a highly motivated and instinctive behavior for cats. The prognosis for complete resolution of this kind of behavior is generally quite poor. The innate response of the cat is to stalk, chase, and attack, and there might be a killing bite (his drawing blood from the caretaker). When this behavior is directed toward family or other pet in the home it needs to be addressed.
The predatory instinct is very difficult to suppress so the best approach to management is to limit his access to your friend. To avoid your friend being "prey" when he/she moves, we need to substitute appropriate prey objects for him. Considerable time playing "bird on a string/pole" and chasing laser light should refocus his attention away from your friend. He might be trained to fetch a ball or toy mouse. Chasing a ping-pong ball can occupy a cat such as he and you might find catnip-containing "chase toys" in the pet store that may lessen his dependence on your friend as prey. Unfortunately, there's no quick fix for inappropriate prey behavior but the above should be helpful for you to at least ameliorate the problem. Please respond with further questions or concerns if you wish.