An idea I saw on another RP board I frequent: a relationship scale!
Organize all your relationships all in one place, rather than awkwardly cluttering your character sheets. This way, you can replace your enemies/allies portion at will, and you'll have a sliding spectrum instead of it being black and white!
Feel free to add your own categories or make suggestions. You can post it here so that we can see how a bunch of characters feel about each other, or put it on your own character sheet elsewhere (or both, feel free to do this). I'm probably going to post this in my writing table of contents thread, but this is especially helpful for folks who do a lot of RP with incestuous "canon", long-running campaigns, and so on.
NOTE- You are MORE than encouraged to put the same person in more than one category!
Family: (You are biologically related or have direct family ties to these people. Otherwise, your living situation / relationship is familiar and extreme enough to use the word "family," like a parental guardian, fiance, etc.)
Through Rumor: (You've heard of these people, but have not actually met them.)
Acquaintance: (You've met these people, but only a few times. Or, you don't know them well enough to call them friends or enemies.)
Friend: (You're friends, but you're not "close.")
Good Friend: (You're close to these people and are fond of them. They may not be your best friends, but you have a special place for them in your heart.)
Best Friend: (You could not imagine what your life would be like without these people's friendships. You love them, even if it's not in a romantic way.)
Lust: (You don't know much about them, but you think of them naked and get... a little excited.)
Crush: (You know at least a little about them and get that hot, tingly feeling when they're near.)
Romantic Love: (They inspire you. You adore and admire him/her, and crave for their affections. Your concern for them is deep.)
Relationship: (Whether it's love, tolerance for whatever reason, or blind lust, you are in a relationship with this person. Or these people!) [STATUS: boy/girlfriend (short/long term?), fiance, spouse]
Love/Hate: (The classic. Can't live with them, can't live without them- comical or angsty.)
Two-Faced: (You lie through your teeth every time these guys ask what you think of them.)
Lost Touch: (You may care for them greatly, or not be interested anymore. Either way, you're on different tracks right now. Or permanently.)
Annoyance: (These people rub you the wrong way. Mild dislike or tolerance.)
Dislike: (You don't exactly hate them, but you can't stand being around them either.)
Hate / Enemies: (Just hearing their name pisses you off.)
Seething Hate / Sworn Enemies: (You live to see them die.)
Sage / Superior: (These people are your teachers, elders, authority, etc. You must regard them with a measure of respect, whether or not you want to.)
Business: (These people conduct important matters with you. You see them to get stuff done. You may or may not care about their well-being.)
Student / Inferior: (You guide these people, or you feel they are inferior to you- which may not necessarily be a "negative" thing.)
Not... Sure: (Uh... you... really don't know what to make of this person. Your relationship with them seems to change on the hour. That, or they're just really... weird.)
It's Complicated: (So complicated, actually, that none of these categories can really nail it.)