Note: any bonuses mentioned should apply only if the attribute in question grants at least a +1 bonus.
Earth: a character who chooses an earth affinity for Strength will be broadly built and bulky, with strong bones. He will deal +1 damage with close combat weapons.
Fire: as if consumed by a flame from within, a fiery character will be tall, and wiry, with hardly any fat whatsoever. In combat, he will fight with ferocity and fury. When he rolls a critical hit, use dice one category higher, e.g. D4 becomes D6 etc.
Air: rather slim of build, with light bones and long limbs, characters with air affinity in their Strength field will be athletic and able to use their strength to its best effect. Thus, they jump farther and higher, can throw better and more accurately. This might also grant a +1 bonus to Tumble.
Water: the character’s body will be well proportioned and well rounded, and generally healthy-looking. He will be vital and his strength will not fade quickly. His muscles will tire slower, grip be stronger (+1 against disarm?) and he will be able resist spells, circumstances and abilities that would reduce his strength better (e.g. receiving +1 to the saving throw in question if a spell or ability like Ray of Enfeeblement allows one)
Earth: The character is very precise of movement, stable and hardly wasting even a twitch in his eye corner. Thus, while not a particularly elegant dancer, he might place his steps perfectly, his handwriting would be balanced and legible and items he crafts symmetric and hardly flawed. Thus, he might ignore a point of negative circumstance modifiers like slippery ground, and receive a +1 bonus against being tripped.
Fire : hot-blooded, with a temper to match his affinity, the character will always be in motion, with heart rates high above normal, always fidgeting with something, restless and active. Yes, he would make the perfect metal drummer. The benefit is an increase in initiative, one or two points.
Air: used to travel, long trekking or running for his life, the character might actually have learnt to enjoy it - with the wind as a companion, combing his hair and whistling a swift song. He simply enjoys the chase. Thus, add 5 ft. to his base speed.
Water : of serene appearance, fluid and elegant in his movements, the character would make a great dancer, for his is the grace of a cat strolling at night. While ones with earth affinity stomp along, the fiery stride, and the children of the wind seem like leaves swept by a sudden gust, a person with water affinity will seem to float by, and are the ones most likely to receive slow motion entrances. They receive a synergy bonus of +1 when using skills like Perform to dance, and can use their dexterity instead of charisma when the motion is the most important factor. As well as that, their body language is more difficult to read, and they will appear to have a very pleasant "tone" when using sign language. As well as that, you are a better swimmer, thus add +1 to your Swim skill.
Earth: like with Strength, a person with earth affinity in this field will be large and bulky (this makes for truly huge fellows if both STR and CON have the earth affinity and high ability scores). Seeming rather slow, still the amount of punishment he can take is unmatched. This might either count as having an armor bonus of +1, or grant the Toughness feat free at character creation.
Fire: when a flame is roaring in your heart, you care little about whether a blizzard is whipping chilling ice needles in your face, or the sun tries to fry you crispy. Either you were bred in the extreme north or south, or you are plain stubborn or just crazy. If you are a northerner, you’ll be hairy and well padded, if a southerner, then darker of complexion, and if just crazy, let your imagination run wild. Northerners gain a damage reduction of 2/- against cold, southerners against heat. Crazies gain a 1/- damage reduction against both heat and cold.
Air: you are lively and active, though smaller of build (or tall and slim), you are filled with vitae and vigor. The one to stay awake longest, get up first and complain after a football match whining "one more? Please?". If a kid, you are impossible to baby-sit, as your caretaker will tire long before you do. The same is true for adults, but for different circumstances. The character will have to sleep one hour less in general, and can exert himself longer. If a barbarian, his rage will last one round longer.
Water: you are vital and healthy, and simply don’t have the little problems with acne, indigestion or a common cold. Your smile flashes a blinding white, and dandruff stays miles from your hair. Likewise, spoilt food will not send you running for the bathroom, and the assassin will use a double dose of venom on you, just for sure. This translates into a +1 bonus to fortitude against poison or disease.
Earth: pondering and analytic, you will approach problems with tenacity and resolve. The puzzle that would beat you was not yet made. You’d be a good mathematician, or stone circle programmer (if not for that heroism thing). You are stubborn, a person of fact and principles. And yes, you are (almost) immune to boredom. This might add +1 to Concentrate, and solving puzzles.
Fire: chaotic to the extreme and inquisitive, you are a swift learner, but tend to suffer from impulsiveness and a great curiosity that might be your undoing. You tend to jump from theme to theme in conversation, make leaps with your insight, but also lose yourself in trivialities, displace your notes (or spare underwear) and get detracted from your goal. You love entertainment in all its forms, and lots of the things you do are just for fun. You receive a free skill point at character creation and another one every three levels thereafter, and learn new spells faster.
Air: a visionary and friend of the muses, you see far beyond the horizon. Almost like a psychic, you can see way the future might be, or the flaws in a piece of art that was proclaimed flawless. While your imagination might create works of art and lead men to greatness, or create new philosophies, you will never be content, always searching, and this will gnaw at your sanity. Actually, it would gnaw if there was any. You will be prone to mood swings, depression or manias. You will gain a +1 bonus to artistic endeavors, and the GM might be a little less skimpy with the info.
Water: you are calm and understanding, a truly balanced person. Knowing what is important, you can concentrate on what is necessary. While you are able to see things realistically, you know the value of fantasies. You are hard to unnerve and there is little that scares you, for you see things as they are. You receive a +1 bonus to saves against fear, and, if a mind control spell’s demands are particularly unreasonable, also +1 to saves against that. If you are a spellcaster yourself, you may still use 1st- and zero-level spells when controlling a spell that requires full concentration otherwise.
Earth: the only true understanding stems from rigorous learning and repetition, at least that is what you think. You have read the masters’ works and understood, and memorized them by heart. The wisdom of the ancestors and mentors guides you today. Certainly, you will not repeat errors done by those before you! You may be a little too set in your ways though, and sometimes lack imagination. The character has excessive access to book smarts, and a great memory.
Fire: why listen to mantras chanted by old men too self-absorbed to see the world for themselves? You are innovative, a pathfinder of thought, quick of wit and never caught unaware. You sense trouble when it’s about to hit you hard.
Air: why learn from books when the world is there plain to see? Not yesterday, but here and now is most important for knowing what to do. You are very perceptive and alert. This grants you a +1 bonus to Spot, Listen and Search.
Water: you have felt many emotions yourself and know what stuff they are made of. With deep understanding of the human (elf, goblin, little purple thing) psyche, you can discern the emotions of others and act accordingly as to avoid angering them, or hurting them even more. Likewise, you know what levers to pull when the need arises, but still you are careful not to hurt the feelings of others. This grants +1 to the use of Diplomacy, Sense Motive or Bluff.
Earth: a strong individual, full of character and imposing, few dare to argue with you. Your word is trusted, and others flock to your side seeing the leader you are. You are likely to be a (wo)man of principles. While you may be excellent at leading, take care as not to smother others with your presence.
Fire: you are truly charming and erotic to the core, with the looks to match this. Given a high charisma, others will either pant or be green with envy. Young knights will fall to their knees, mistaking a hormone rush to their head for the love true, and old cackling priests of death-reeking gods will remember their youth when there was something else as well. The drawbacks are numerous as well, though - you will attract lots of attention, sometimes unwanted, and will find it hard not to be judged by looks, but for your inner values. Also, envy can be dangerous in many ways.
Air: you are charming and witty, and can raise low spirits, brighten a sour face or cheer up a band of kids. Your humor and puns are both loved and feared. While you will be a welcome sight at most parties and children will genuinely love you, you might be seen as immature, irreverent and unable to be serious (who would want to, anyway?)
Water: you are very pleasant, and seem trustworthy. Crying kids will tell you who stole their teddy, your roommate will spill her guts about her lost love, and generally people will come to you to seek comfort. You are to spirit as a balm is to the wounded body - you soothe and help cuts heal. Children will fall asleep when placed in your lap and stray dogs will come and lick your hand. Rarely will anyone find you annoying, and rarely will you be the target of aggression.
Additional Ideas (3)
I've had some difficulty imagining all the combinations, so some of them have slapstick examples of how the low attribute plays a role in the character's life:
Charisma - being between people:
- Earth - has problems voicing own views, is usually slow-spoken, often stubborn. Some people consider him dumb, the character may be tolerated with contempt.
- Fire - seen as fleeting and unreliable, and highly irritating. Evaded if possible. The classical elephant in a china shop, a faux-pas is never too far. "What?"
- Air - aloof and distanced from the rest of the world, often seen as arrogant and haughty. Can easily harm people, if opening a sensitive topic.
- Water - what a boring and unimportant guy, the main problem is to get people pay attention to him. Just don't mind him. "Excuse me... could I... errr..."
Intelligence - facing a problem:
- Earth - has a hard time to shake off old views and accept new things, as facing new problems. Does not have to be dumb, just thinks too slowly, needs to ponder on everything.
- Fire - can't concentrate, something else too soon occupies his mind.
- Air - doesn't go beyond the surface, finds simple solutions that tend to overlook important details.
- Water - tends to consider too many unimportant details of the problem, and often becomes lost in the special circumstances of the given case.
- Earth - fails to use own potential. Can be large, but then it is fat, not muscles.
- Fire - the energy runs out too soon. What may succeed at the first try, will not on the second. Can be tall, but is usually thin.
- Air - physically, the character is like air for many people... not worth minding that little guy. Tends to be overly sensitive to pain.
- Water - gets sick easily. Needs one hour sleep more to rest.
Dexterity - seen while handling a fragile object:
- Earth - stuff has a tendency to break in his hands, especially risky with high Strength. Never throw him things he is supposed to catch.
- Fire - accidentally drops or bumps into things. "Ooops... sorry."
- Air - the item almost falls, but after several attempts is caught. However, something else breaks in the process. If very low Dexterity, the original item breaks as well.
- Water - dangerous to machinery, has the unwitting (and sadly, unusable) knack for sabotaging complex machines. Even simple items are not safe from him. Looses important parts or moves them around in some weird way. This is the guy that absent-mindedly shuffles a Rubik cube, and no one is able to shuffle it back anymore. Also has a tendency to produce complicated knots.
Earth - Like sand pouring through a sieve, or blown on the wind, this persona is lacking in substance and cannot stand their ground. They are at +1 difficutly to resist knock-downs, knock-outs, or other physical challenges
Water - The persona is ungainly, their limbs seemingly too long or two short or one seems longer than another. Their health is less than perfect due to the inhibited flow of the vital humors. +1 difficulty to resist disease and prone to bruising.
Air - With as much as this persona huffs and puffs about it would seem they are strong with air, but it simply that they cannot get enough. Running and long trekking are out of the question and even a fast jog or hustle is a good way to end up panting, red faced and sick. +1 difficutly for overland travel or any aerobic or long term activity. Dont go swimming.
Fire - without focus, without fury there is no point to strength. This persona lacks commitment behind their actions and their strikes are accordingly weaker. If an attack uses a D6 it is reduced to a D4. There is no strength without passion!