You know how ALL chromatic dragons are some flavor of evil aligned, ALL metallic dragons are good aligned, and ALL gem dragons are neutral aligned?  Well, what would happen if you role played a debate with a dragon in which you convinced it to change its moral alignment despite its inherent nature from birth?  Kind of like how Paarthurnax in Skyrim decided to change his ways.

More nuanced, would they shift to their corresponding type if they shifted alignment?  Like, would a red dragon metamorphose into a gold dragon if their moral alignment changed? Is that why all chromatic dragons are evil, all metallic good, and all gem neutral? Or is it just a tendency in which an evil bronze dragon is rare, but not impossible?  Would a white dragon raised from hatching to adhere to the idea of treating others as it wants to be treated still veer towards dim-witted selfishness, but fight those tendencies through the cultivation of moral philosophy? Or would a green dragon shift into an emerald dragon if it became more reclusive and neutral?

Can a tiger change its stripes? Can a dragon change its scales? Or are they locked into their way of thinking and no amount of intellectually stimulating conversation will change that?

What is the greater good?  Someone born to goodness, or someone who chooses goodness despite a nature or circumstances that pressure them towards evil?

What about divine intervention?  Could Bahamut turn a gem dragon good? Or metallic and good? Think how in Shinto the Buddha turned Radien and Fujin from evil demon gods to good protector gods.

They'd stay the same.

From a mechanic standpoint, Fizbans amended dragons to add the "Typically" piece before any stated alignment.  So while a creature might have a natural disposition to swing one way, it isn't all for nothing and it doesn't mean that intelligent creatures can't change.

So to answer, not all metallic dragons are good, not all gem are neutral and not all chromatic are evil.  Not anymore.

In some settings they never were. Eberron, for example.

Fisban’s gives examples of Traits and Bonds for dragons opposite of their usual alignment, so presumably the scales don’t change. 

Damn.  There was a part of me that was hoping they would.  It would have been narratively interesting.

You know how ALL games of D&D are played with the exact same fidelity to ALL the lore and mechanics for ALL the monsters?

Me neither.

Dude, if you want to have dragons change their scales, and you're the DM, there's nothing stopping you from putting that sort of phenomenon in place.  It sounds sort of cool.  I mean Draconians are "evil" corruptions of metallic dragon eggs.  Between that notion, the draconic essence manipulated by Drake Warden rangers, a bunch of the Dragon variants (ooze and ghosts even Ilithid derived) ... there's definitely something fluid about the nature of dragons, if you want there to be.  I mean per Fizban's, if a DM wants it so, a dragon can turn a humanoid into Dragonborn, I don't see why a Great Wyrm couldn't twist a draconic essence to its will.  I guess I sorta see Great Wyrms and Tiamat and Bahamut being sort of D&Ds Unicron and dragons are like Deceptions or any cybertronian in Unicron's thrall.  Heck if Unicron can turn Optimus Prime into Nemesis Prime, dang straight a power wyrm can make a chromatic metallic or vice versa.  This sounds fun!  Especially if the convert was once a nemesis and not a patron of the party or more tragically vice versa.  

So, why not? it's sorta cool, and might be something I'll play with in my current dragon themed game.  It actually would fit well since the main broad conflict is a sort of draconic lore orthodoxy (the Tiamant/Bahamut schism) actually revealed to be an ideological narrative employed to suppress the true much more fluid nature of draconic essence (Tiamat used to be much more colorful, until her nature was mutilated by Bahamut and others wishing a more consistent universe ... which to them seemed a good idea at the time ... anyway Tiamat used be simultaneously much more unified and manifold ... and someone got the PCs onto the idea that maybe that can be restored, though they need to be careful, some of the "lost colors" are even more wrathful than Tiamat and/or don't want to be found).  

You'd want to determine how exceptional such conversions are.  Whether these are acts of volition or conscience, and/or whether they are the results of being subjected to powerful magics.  There's nothing in the rules that I know of that says this happens, but it doesn't mean it can't happen.

This is a good topic for Story and Lore, see if you can move it there.

Brainstorm terminology draconic alchemy or drachelmy is experimentation with draconic essence with the intent to fully reveal the prism and substance of that essence ... though is largely applied in the transformation of dragons from one variety to the next, it's needless to say controversial stuff.

I'm against the idea that dragons change their type when changing alignment, as it feels too much like pokemon... childishly unrooted in nature. Not that you couldn't tell that story--just, I wouldn't. The idea, however, of dragons encountering moral quandaries does strike me as entertaining and as food for thought. If an evil dragon converts to good, what becomes of its hoard? If a neutral dragon converts to evil, what happens to it's psionic powers--are they twisted by it's newfound lack of equilibrium? If a good dragon converts to neutral, what do all the other dragons say about zir?

Do you want them to?

If so, then do it.

There is lore that suggests that emotions can affect the color of something such as the polarizing existence of the Flumph. So, it's not completely outlandish.

Tweak your world. If the scales are an outward appearance of the dragons' Paragon/Renegade or Dark Side/Light Side personalities, why not? The most famous fallen Celestial who became a ruler of Avernus had a serious change in appearance when the alignment changed.

Others might not like the idea, but there's support for the concept if you want it in your game.

EDIT: Both of these minis are Zariel - different alignments.

On the other hand you have Garnet the LG RED dragon that caused the downfall of Myth Drannor in the Forgotten Realms as an example of a dragon with the opposite alignment but unchanged scales. Still it’s your world so do what you like but remember to let the players know as their characters should be aware of their world’s rules.

Quote from Wi1dBi11 >>

On the other hand you have Garnet the LG RED dragon that caused the downfall of Myth Drannor in the Forgotten Realms as an example of a dragon with the opposite alignment but unchanged scales. Still it’s your world so do what you like but remember to let the players know as their characters should be aware of their world’s rules.

I see where you're coming from.  On the other hand, especially with monsters like Dragons, I think there's plenty of room for "Wait, I didn't know they could do _that_" moments.  In fact there's a lot of schools of DMing that prefers players stay away from the Monster Manual (nearly impossible in this day and age), so they can't discover features like chromatic wrath of Tiamat, Platinum Brilliance of Bahamut, or the equivalent given in Fizban's to the Greatwyrms (and the subsequent Mythic actions those features unlock with the Dragon starts "round 2" of the battle).  Whole 3rd party books, most of what Kobold Press puts out (and I'd argue Volo's and Mord's share this conceit) exist to throw monsters at players so that the party doesn't know the monster's rules.  

I still stand by this being a neat narrative surprise or twist.  Their campaign-long antagonist becomes a atoning patron (with cool hoard swag to hand out) or a former patron turns out to be the new mysterious adversary (and it wants its cool hoard swag back).

Part of the discovery in a game could be discovering the magic and rituals that may engender such transformations.

(Again, bias since my main campaign theme is restoring Tiamat to a form she held prior to her mutiliation into her present form at the claws of Bahamut and some co-conspirators who've been silent about the matter for most known history and pre-history ... and don't get started or Sardior, things are just different from the way they were portrayed in the books most readily at hand because of that adage about who gets to write history).   

That is the distinction between RAW lore and home design in a nutshell. By RAW lore (Garnet) the scales don’t change to suit the alignment, by home design you can rework that however you want. The one thing to be careful of is altering the mechanics - if the AC or HP change not just the color of the scales then you have to adjust the CR as well.

Using ideas from the Forgotten Realms’ Dracorage, many dragons did have alignment changes. I’ve just finished Dragons of Faerûn, and saw at least five dragons that felt bad about their hands (claws?) in the destruction that happened therein.

One of my favorite things about dragons is that they show their alignment on their scales and can’t hide it, but I changed dragon lore for my personal games so that instead of scales, it’s a dragon’s eye color that determines its alignment. I had dragons born as blind, and their alignment changes with their personality as they mature. Whatever they’re most in line with, alignment wise, is the color their eyes turn. Their scales stay the same and their species is the same, but their eyes betray their alignment. I think it would be really interesting to see a dragon undergo a physical transformation after a severe moral shift. I would treat it like Zuko from AtlA, where he becomes ill and has delusions for a bit before adjusting to his new morality set? If that makes sense? It’s a really cool idea though, and I like the idea that their morality isn’t set in stone.

Quote from cynophobia_ >>

One of my favorite things about dragons is that they show their alignment on their scales and can’t hide it, but I changed dragon lore for my personal games so that instead of scales, it’s a dragon’s eye color that determines its alignment. I had dragons born as blind, and their alignment changes with their personality as they mature. Whatever they’re most in line with, alignment wise, is the color their eyes turn. Their scales stay the same and their species is the same, but their eyes betray their alignment. I think it would be really interesting to see a dragon undergo a physical transformation after a severe moral shift. I would treat it like Zuko from AtlA, where he becomes ill and has delusions for a bit before adjusting to his new morality set? If that makes sense? It’s a really cool idea though, and I like the idea that their morality isn’t set in stone.

 I love it! Imma adapt that to my dragon lore too (if you don’t mind 😊).

I would argue that if dragons are primeval manifestations of the prime material plane, they don't exist like humans. They aren't good or evil. The are elementally good and elementally evil. (If you weren't aware, that the Temple of Elemental Evil is full of evil elementals is a pun.) This view is not supported in the books anymore, this is true, but it's more interesting.

A dragon can't change its alignment. No more than you can decide to not be hungry or not need to sleep. Their alignments is a fixture of their existence. I think it's important to keep some life alien to our own frame of reference. A dragon is not a human being but big and scaly. It is a big, apparently multidimensional, primordial being and it does not see the world like we do.

Quote from Verenti >>

I would argue that if dragons are primeval manifestations of the prime material plane, they don't exist like humans. They aren't good or evil. The are elementally good and elementally evil. (If you weren't aware, that the Temple of Elemental Evil is full of evil elementals is a pun.) This view is not supported in the books anymore, this is true, but it's more interesting.

A dragon can't change its alignment. No more than you can decide to not be hungry or not need to sleep. Their alignments is a fixture of their existence. I think it's important to keep some life alien to our own frame of reference. A dragon is not a human being but big and scaly. It is a big, apparently multidimensional, primordial being and it does not see the world like we do.

 What do you mean, not in the books anymore?  I don't recall a point where that was ever supported by the books.

Quote from 6thLyranGuard >>

Quote from Verenti >>

I would argue that if dragons are primeval manifestations of the prime material plane, they don't exist like humans. They aren't good or evil. The are elementally good and elementally evil. (If you weren't aware, that the Temple of Elemental Evil is full of evil elementals is a pun.) This view is not supported in the books anymore, this is true, but it's more interesting.

A dragon can't change its alignment. No more than you can decide to not be hungry or not need to sleep. Their alignments is a fixture of their existence. I think it's important to keep some life alien to our own frame of reference. A dragon is not a human being but big and scaly. It is a big, apparently multidimensional, primordial being and it does not see the world like we do.

 What do you mean, not in the books anymore?  I don't recall a point where that was ever supported by the books.

Can I get a list of canonical lawful good red dragons?

There's a total lack of canon Lawful Good bugbears, but that doesn't prove that bugbears are "elementally" evil.  Just that there aren't any good-aligned NPCs.  There's barely any dragon NPCs in 5E to begin with, but older editions  did have some good red dragons: Eberron had a few, the 3.5 Book of Exalted Deeds had one, 2E had multiple between the Council of Worms setting and various articles in Dragon magazine, and Mystara didn't directly tie alignment to scale color.

Heck, the game has canon examples of fiends who are good-aligned, and they're literally made of evil.  The idea that a dragon's alignment is more immutable than a demon's is utterly silly.

Quote from 6thLyranGuard >>

Heck, the game has canon examples of fiends who are good-aligned, and they're literally made of evil.  

Who dat? 

But to the actual topic, Fizban's definitely allows a broader range of alignments among color/metals/gemstone dragons (like, there are tables), which goes against the notion of dragons in 5e being "essentially" or "elementally" aligned.  Though dragons being essentially of one alignment or the other goes back to the earliest grouping of dragons into a chromatic/metallic sort.  It's a world building concern, not a right or wrong portrayal thing.

In my game, metallic dragon's think they're the good guys, but some are wondering how they're faction chose to represent or manifest itself as reflective of precious metals associated with wealth and luxury ... wait, I went deeper into this already in this thread two months ago.  Just scroll up.

Quote from MidnightPlat >>

Quote from 6thLyranGuard >>

Heck, the game has canon examples of fiends who are good-aligned, and they're literally made of evil.  

 

Who dat?

A'kin the Friendly Fiend from Planescape is a good-aligned arcanoloth that lives in Sigil.  He's probably the most famous example.  Beyond him, there were some less important NPCs in Planescape, and a Succubus Paladin in 3.5.  Fall-From-Grace in the video game Planescape: Torment is officially listed as Lawful Neutral but action and attitude wise she's good in everything but name.  The Planescape sourcebook Faces of Evil: The Fiends actually had sections about all three major branches of fiends (demons, devils, and yugoloths) that turned good.  It was a rare occurrence, but the Planes are big and there are a lot of fiends.