People are not always what they seem. Respect the otherness of the other and don't be sure you know who they are. It is hard enough to know who you are. And remember that other people are the ultimate drug -- as social mammals we are incredibly influenced by the people we are around and that influence is on multiple levels that often escape our awareness. The I Ching puts great emphasis on choosing your companions with care. Avoid associating yourself with people with whom you wouldn't trust your life. Solitude is usually preferable to unworthy companionship.
See A Guide to the Perplexed Interdimensional Traveler for a discussion of I Ching Hexagram # 44, and the principle of meeting halfway as the touchstone for human relationships. also relevant: Stop the Hottie! Casting Precious