Some pirates hold to a 'code' of sorts, which implies standardized behavior. But the truth of the matter is that anything goes. If you choose to run, a pirate may give chase, or they may not. If you give in and pay the money, there is no guarantee that the pirate won't shoot you anyway, or try to extort from you again on the return trip. After all, you are dealing with a criminal. On the other hand, some pirate encounters can prove to be beneficial. Pirates have been known to take new recruits from time to time, or they may know of profitable trade routes. Payment of their extortion demands could also gain you a temporary escort if you are a smooth enough talker. Take it all with a grain of salt and have a good time with pirate encounters. It's part of the game, and it is supposed to be fun.
Most pirates can be found in [[gray space]]. If you are afraid of being pirated, you should probably stick to your nation's systems where you will be guarded from pirates.