Everyone with more than one alignment, raise your hand (3.5e Variant Rule)
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See the Netbook of Alignment for more articles about alignment.
OK, everybody knows the basics on alignment. All creatures get to pick one; if your intelligence score is below 3, you get stuck with neutral - hungry, otherwise you pick one from nine options. Or do you? Officially demons are always chaotic evil, yet even in canon 3.5e you get oddballs like the infamous Succubus Paladin. How can you have "Chaotic" and "Evil" in your subtype and a class only available to lawful good applicants? What does the SRD have to say? It's not exactly clear on this admittedly questionable issue.
Personally, I like the D&D alignment system, but I have some serious gripes about it. It's just too confusing in weird situations, which can become all too common. As someone who is more a fan of fiction in general than RPGs, its seems unfair aren't good rules for dealing with characters who are designed around subverting the stereotype of an alignment, like a sympathetic villain. I am proposing some optional rules as add - ons to the alignment system for everything from people whose behavior straddles alignment boundaries to creatures whose biology is in some way alignment - related, as well as rules for using other alignment systems in addition to the standard alignment system.
A character can have a secondary alignment that represents how they deviate from the stereotype for their main alignment. A common situation might be a character who fluctuates between two alignments. Usually one of the two is more predominant, so that is the character's "actual" alignment, and the other is the tendency.
 Tendencies and the Alignment Chart
 Adjacent alignment
The most common situation will likely be that a character's "actual" alignment and "tendency" are next to each other on the alignment chart. This can help to show on which side of one's alignment "box" one falls, and can both resolve and create conflict. EXAMPLE: A friend of the party is on trial for a crime. Both the party and the judge know the friend is not really a bad person and their family will be in bad spot if the friend gets a harsh sentence, but the town is struggling and the judge believes that the friend must be made an example of to reinforce order. The party's chaotic good member is considering staging a jailbreak. A lawful good character with lawful neutral tendencies will argue that the suffering of the friend and his family, while unfortunate, is less important than the good of the town and maintaining order. A lawful good character with neutral good tendencies would argue that there must be a way to work within the law to help their friend.
Neutral tendencies might indicate a character who is not completely loyal to their alignment, a political moderate with a regard to alignment, someone who is new to the alignment and not yet firm in their beliefs, or, conversely, an older, experienced character who is wise enough to be subtle. Children of creatures who are born neutral may usually be this way.
Non-adjacent tendencies might indicate a split personality, divided loyalties, or a character that is not comfortable with their own alignment. For example, an unprincipled character might be chaotic neutral with neutral good tendencies.
 Numeric Alignment Calculations
Some homebrew systems assign numeric values to character alignment. The advantage is that you get a continuum rather than nine choices, you can score characters' attitude and deeds to determine their alignment numerically, and it helps provide a rule for deciding when to permit an alignment change.
 Additional reading
 Inherent Alignment
Officially demons are always chaotic evil, yet even in cannon 3.5e you get oddballs like the infamous Succubus Paladin. How can you have "Chaotic" and "Evil" in your subtype and a class only available to lawful good applicants? There are at least three possibilities: (1) Don't worry about it (2) Always Means Always, and succubi paladins only exist in legend, or (3) it is possible to have multiple alignments simultaneously.
As mentioned above, the rules say in general, all creatures get at least one alignment. That alignment is what you believe in your soul and act upon, and works just like the rules say. I call this a creature's actual alignment. You get your actual alignment from having the ability to think, even if your thought process is limited to "prey = kill", "command recieved. initiate new action...." or "duh". As long as a creature truly has free will, it is within the laws of game physics for it to change its alignment at any time. Some creature's personalities may make this extremely unlikely, however.
The other alignment, if there is one, is not about who you are in heart and mind, but who you are in terms of 'supernatural biology'. I call this a creature's inherent alignment, and you get it from the fact that your creature type or subtype is inherently associated with one of the nine alignments. Changing one's inherent alignment would nominally kill a creature, since it would be like replacing a human's blood with that of a reptile. A creature's inherent alignment thus cannot be changed except under very weird circumstances such as a wish spell, being killed and reincarnated as a badger, ascending to godhood, completing a beyond - epic quest, etc.
 Who has an 'inherent alignment'?
Any creature with a type or subtype of lawful, chaotic, good, evil, celestial, fiend. Also, any fundamentally supernatural or magical nature and an alignment modifier of 'always' is likely to have an inherent alignment. It's the DMs call whether or not a creature is fundamentally supernatural or magical. For example, elves, unicorns, and centaurs are more magical than humans, but less magical than beholders.
Outsiders are "at least partially composed of the essence... of some plane...". If that plane is by definition associated with a specific alignment, the outsider will have an inherent alignment from that plane. Also, any outsider whose subtypes include "lawful", "chaotic", "good", "evil", or "Neutral", or an 'Always' alignment modifier has an inherent alignment.
 The Undead
Undead and 'negative energy' are "inherently Evil" under The Crawling Darkness option. That means all undead, as well as creatures native to the negative energy planes, get an inherent alignment, and an evil one at that. Neutral evil is generally the default; undead that would logically be always lawful evil (such as Revenants) or chaotic evil get those for inherent alignments. Vampires, liches, etc, should be allowed to change their actual alignment between the three evil alignments as a human would, but there may be restrictions or penalties for changing to a non - evil alignment. If you prefer Playing With Fire, the default undead alignment becomes true neutral rather than neutral evil. However undead created through evil magic or evil acts will still have an evil 'inherent alignment'; also, it is possible not all undead have an inherent alignment under this system.
 Multiple Alignment Characters vs. Alignment - Based Magic
Most spells and other abilities that affect, detect, etc. law, chaos, good, or evil work against BOTH actual and inherent alignment. Thus a Succubus Paladin would be affected by smite law, smite chaos, smite good, AND smite evil. Some spells and spell - like abilities (Wish, Limited Wish, Know Alignment, Detect X, etc.) might detect actual or inherent alignment, both, or neither, depending on the wording of the homebrew rules and spell description, how the spell is performed and worded by the caster, and possibly a die roll or the whim of the applicable deity or DM.
 Prestige Alignments
Prestige alignments work like prestige classes, so that to gain one, one has to meet a set of alignment - related preconditions. The main advantage and disadvantage of prestige alignments is they come with a preset code of conduct thats a lot less vague than the standard alignment.
A very good, but often annoying, person who regards obeying the law as just another part of what it means to be good.
- Examples: Superman, traditional knights in shining armor like King Arthur and Prince Charming, Aslan.
- Requirements: Must be of lawful good alignment. Must have refused to break the law at least once in defiance of one's friends.
A tough good guy who breaks the law in order to protect decent, orderly organizations and innocent lives.
- Examples: Dirty Harry, Batman, Robin Hood, Harry Potter, Zorro
- Reqiurements: Must be of good alignment. Must have broken the law at least once to help bring a worse lawbreaker to justice.
A jerk with a heart of gold who reluctantly agrees to negotiate, and later ends up rescuing the hostages and pocketing their ransom.
- Examples: Hancock, Han Solo, Jayne, Kar; possibly Jack Sparrow, Lina Inverse, and Haley Starshine.
- Requirements: Must be of non - lawful and non - evil alignment. Must have committed at least one act of selfless heroism willingly after having rudely refused to do so shortly before.
A hedonist who just wants everyone to have fun.
- Examples: "Bottle Fairies" like Liriel from Drowtales.
- Requirements: Must be of chaotic neutral or true neutral alignment. Must have once gotten into trouble because of an "innocent" celebration.
A selfish jerk who cares for nothing except his own power and wealth.
- Examples: the typical TV drama depiction of drug lords, villains with good publicity, and corrupt corporate executives.
- Requirements: Must be of non - good alignment. Must have betrayed a friend at least once purely for personal gain.
A corrupt but honorable, gentlemanly villain.
- Examples: the typical TV drama anti - villain, anti - hero, or knight templar, some depictions of Devils.
- Requirements: Must be of non - good alignment. Must have at least once said something like "How despicable, even I wouldn't stoop that low!" and meant every word.
A truly nasty person who lives for causing pain and suffering. Many gaming groups don't allow diabolic PCs as they are more evil than the evil alignments.
- Examples: the typical horror movie serial killer, many fiends, the Joker in his darker portrayals, Naraku from Inuyasha.
- Reqiurements: Must be of evil alignment. Must have committed at least one act of sufficient evil that it appalled even other evil people, for no reason other than pure enjoyment.