I've noticed that people generally good at practicing reciprocity -- the act of giving back the same treatment that someone has given you, whether it's good or bad. If you give someone a gift for his birthday, he'll likely give you one once your birthday rolls around. If you give him nothing, it's probably best not to expect anything in return. Very rarely do people give without first getting something themselves. More often that not, acts of kindness are rooted in those that came prior. It's a "you do, I do" dynamic. It's almost like playing tag. The same goes for negative behavior. If someone does something to upset you, your first instinct is to do the same to them. In reality, though, the best relationships are those where you do someone nice for someone else and expect nothing in return . They'll felt a sense of duty to return the favor, though, because we don't want to create the perception that we're unappreciative or taking...