If I cast find familiar, what is the creature's alignment? I ask because the majority of entities that change forms retain their alignment and the familiar is simply a spirit assuming the form of a beast (or Pact of the Chain form).
You gain the service of a familiar, a spirit that takes an animal form you choose.
One way this is relevant is the ability for a Pact of the Chain familiar (such as Imp) to damage a Rakshasa with a magical piercing weapon.
Neither Find Familiar nor Pact of the Chain specify changing the alignment, or any other stats of the familiar.
Sprites and Pseudodragons are among the available familiars for Pact of the Chain, which are "good" creatures that could circumvent the Rakshasas resistance.
At your DMs discretion he may allow you to determine the alignment of your familiar, given that there is no guidance as to whether a found familiar is an actual imp/sprite/cat etc. in every way or if the spirit taking that form temporarily retains elements of its "true self" (alignment, personality etc.).
In each case the spell describes, the spirit's variable characteristics are chosen by the caster:
You gain the service of a familiar, a spirit that takes an animal form you choose... the familiar has the statistics of the chosen form, though it is a celestial, fey, or fiend (your choice)...
and the spirit is unfailingly loyal to the caster:
Your familiar acts independently of you, but it always obeys your commands.
The implication appears to be that the spellcaster has absolute determination of both their familiar's actions and its very nature -- which is to say, control of its alignment, at least for creatures which have an alignment (like the Imp).
However, the Alignment entry from the Monster Manual reads,
Many creatures of low intelligence have no comprehension of law or chaos, good or evil. They don’t make moral or ethical choices, but rather act on instinct. These creatures are unaligned, which means they don’t have an alignment.
Since beast-form familiars copy the statistics of the basic creature, and those creatures have low intelligence, they would fall under the guideline of "having no comprehension."
A Find Familiar "familiar" is NOT the creature whose form it takes on and thus its alignment and personality is NOT from the creature whose form it takes on. This is supported from the wording of the spell where the spirit summoned can have its form changed by recasting the spell, thus the same spirit can take on any of the allowed forms, which for a warlock with a Chain Pact could have one familiar spirit which can alternatively take on the form of a pseudodragon and imp.
If the familiar could change alignment by changing form, this not only is illogical but could be abused by allowing the familiar to easier get past alignment restrictions because it could be good, neutral, or evil depending upon which form the warlock chooses. For example, a rakshasa is vulnerable to piercing from magic weapons wielded by good creatures so a rakshasa would be vulnerable to a pseudodragon's piercing attack. Another example is the Talisman of Ultimate Evil can only be used by an evil alignment, thus an imp or quasit could use it. A familiar should not be able to do that, changing its alignment by changing form.
Now, I see it as an oversight that this is not spelled out in the spell. But, the familiar spirit changing form should not change that spirit's alignment and personality. Think about the spell True Polymorph.
The alignment of the familiar should either be non-aligned like an animal or match the alignment of the caster summoning the familiar. As a GM, when I run a game, I have the alignment of the familiar match the alignment of caster of the spell.
If the GM and/or player specifically wanted a familiar of a different alignment, then that could be done through other means than the spell Find Familiar and thus one could make a pact with a real creature that will be that person's familiar. But, the spell Find Familiar would not be part of this. Actually, a familiar gained through such a pact has advantages and disadvantages over the spell version. Look at the familiar version of monsters which can be familiars.
https://www.dndbeyond.com/spells/find-familiar
Adding a few thoughts for consideration to this old thread. For reference, my experience spans all D&D editions from first edition to current.
As previously stated, Find Familiar spell (found in the Players Handbook p240) forces the caster to choose the creature type when they gain the spirit's service. The players chooses if "it is a celestial, fey, or fiend instead of a beast." This choice entirely replaces the original creature type. Now, if one were so inclined to align a familiar, one might use the choice of creature type as guidance. (From the Monster manual the following is true.) Celestial creatures are overwhelmingly Good, Fey - Neutral, Fiends - Evil. (makes sense thematically)
Personally, my experience tells me that I like some of the ideas presented and would use what makes sense for the character running the familiar and for balanced play. For example; If a good aligned character wanted an evil familiar to have role playing moments that create interest for the player, I would consider it. Although, I have a hard time seeing for example, a Celestial Evil Imp.
I'm all for inventive play. However, my experience tells me to steer away from detrimental game mechanics. I don't allow players to abuse a mechanic to bypass a story hook or any reason for that matter. And, swapping alignments around is firmly in the realm of powerful effects such as curses, planar effects, artifacts and the like, not a first level spell that is also a spammable ritual. Magic is powerful but first level spells are not that powerful. That said, I encourage inventive play and work with players to create a live environment that all players can immerse themselves and enjoy their characters and story.
To be sure, the Players Handbook notes the ability for player characters to change alignment. This requires storytelling and potentially role-play to accomplish.
I do like the idea of the caster aligned (makes sense thematically) and the unaligned familiar also since you can essentially transmute its form when you recast Find Familiar. Keep in mind, a familiar is much more than a basic stat block. It is a part of and an extension of the caster.
D&Ders, what ever you decide, have fair fun!
D&D 5E Alignment Information Sources:
Players Handbook - p122 Alignment in the Multiverse "Alignment is an essential part of the nature of celestials and fiends. A devil does not choose to be lawful evil, and it doesn’t tend toward lawful evil, but rather it is lawful evil in its essence. If it somehow ceased to be lawful evil, it would cease to be a devil."
Monster Manual - Creatures
Dungeon Masters Guide p59-60 - Bytopia - Pervasive Goodwill: visiting the plane of Bytopia causes a shift in alignment to NG or LG.
Dungeon Masters Guide p138-139 - CURSED ITEMS
Dungeon Masters Guide p162 - The Deck of Many Things Balance "Your mind suffers a wrenching alteration causing your alignment to change. Law to Chaos, Good to Evil and vise versa"
Dungeon Master's Guide p97 - Oathbreaker paladin atonement rules. "The paladin who wishes to atone must first shed his or her evil alignment and demonstrate this alignment change through words and deeds."
Players Handbook - p122 Alignment in the Multiverse "For many thinking creatures, alignment is a moral choice. Humans, dwarves, elves, and other humanoid races can choose whether to follow the paths of good or evil, law or chaos."
Additional information added here by me from posts by Phil Boncer and from post by Liza's Mentor.
That, as usual, is a DM decision; it is not specified anywhere. The spirit that is summoned to create the familiar is chosen by the caster to be a Celestial, Fey, or Fiend, so as a DM I would have its alignment match that choice. But it isn't defined RAW.
I’d say it’s up to the DM. But an evil aligned familiar usually hints at an evil spell caster and vice versa.
