I'm sorry, your character idea is too awful.

[Angrydad]

A player in my current campaign is playing a gnome barbarian who wields a human sized greataxe. He took a feat to be able to use the oversize ax properly, but it only applies to his axe, no others. I figured this was pretty good character concept and roleplaying so I let him take a few other flavor feats as reward.

My brother is the master of weird characters. In my previous long running game he played a half-elf swashbuckler with 2 distinct personalities. His public "face" was sullen and fairly antisocial or bossy and pushy most of the time. On occasion his other personality would emerge and he'd don a costume with a mask. This second personality was a suave ladies' man full of bravado and charm. He played him much like a superhero, only without any powers, just feats, some creative skill useage, and some retardedly good dice luck.
My brother's current character is a half orc cleric of Yondalla. Yeah. He believes that he's a reincarnated elderly halfling lady and therefore wears a flowery dress over his armor as well as a curly grey wig. Plus, all his healing spells are fluffed as a pat on the back or shoulder with a, "There there, sonny. Have a cookie." Finally, his Intimidate skill is now relabeled as "Scold".

 

[avin]

I will say no to:

1. A very rich mage on an ogre's body (don't ask... GURPS game...)
2. Two players using their ECL to make ONE Ettin... (the idea wasn't so bad in the end)
3. A wizard using a chicken as familiar (and thinking itself a Bard... don't ask, again...)

 

[Mallus]

...Very dapper necropolitan halfling Dread Necromancer (Who would be illegal in just about every way imaginable in 4e . He was even lawful neutral). Intimidate was replaced by "Be obscenely british." His undead were all given names with Jeeves and Charles...

That's terrific... especially the 'be obscenely British' part.

 

[simply not edible]

I have said no to a player wanting to go kobold warlock on me. Then again, it is supposed to be a dragon/scaly-hunting campaign...

Otherwise, I'd allow lots of things. I'm all for the weird stuff. I have, in my d20 Modern campaign, just had my players hunt Nazi's in steam-powered stealth-suits. Said Nazi's had mind-controlled Grey combat drones. This is in 2027, mind you.

They ended up evading most of that final encounter by playing Rick Astley over the mind-control frequency, getting the Grey out of fighting condition.

 

[Rechan]

DM
When floating a gestalt game because I had few players, I had to say no to a Warlock/Monk because the guy said "Hey, I can be some guy from DBZ!"

There was a minor kerfuffle when I was going to run a demon-hunting game and a player wanted a Spirit Shaman (In this instance, spirits wouldn't be all that influential). Incidentally I just made demons constitute spirits.

Player
There's a concept I want to play that constantly gets rejected: A Kobold Paladin. The idea being that he was your standard sneak kobold, but he was caught in a trap, or a situation, and (what he believes), Bahaumet saved him. So he turned over a new leaf, and now believes that kobolds were created by Metallics, but Chromatics corrupted them. So he wants to create his own nest(s), covert his fellow kobolds, and make a good name for kobold kind. For some reason, no one takes it seriously. (I'll have to readjust his combat schtick to suit 4e).

I am a big fan of non-demihuman races. Kobolds (my favorite), Tri-keen (or anything bug-like), changelings and warforged and shifters, oh my! And Undead. In non-Eberron groups, this is generally a strong "no".

Multiple Personalities
I particularly love multiple personalities, but see that most people use them as an excuse to do crazy things. I prefer the general creepy factor, as well as just the roleplaying challenge. But then, I'm the type of guy who would enjoy playing a Tri-keen just so I can use insect-like body language at the table.

I can see there being different ways to go about it, for instance the character being an "Open Vessel"; entities can possess the character, so you have the character's "base" personality, and the personality of whatever entity is possessing him at the time. There's also the Shapeshifter, who doesn't have multiple personalities so much as he has a few favorite "Identities" that he likes to switch between. He's not crazy, just a really good actor with three or four favorite faces/personalities that fit the situation. (I play a good changeling, let me tell you).

 

[Stormborn]

I have a player who loves to roleplay. She comes up with great characters. They almost always fit the campaign just fine. They are almost always charming dashing sorts, of either gender, who are designed to be the party face and utility person.

The problem is: she cannot run these characters in a way that makes her happy. She just cannot roleplay on the fly that kind of personality, and she would far rather attempt to do so, typically making some horrible gaffs along the way,than simply say something like "My PC is going to flatter the guard into letting him speak to the prisoner. >Rolls appropriate skill<." If she would do the latter she would have less frustration.

The second problem is that she so focuses on character development and backstory she is often ineffective in combat. That frustrates her as well. This tends to mean a week between sessions of the two of us in heavy IM or e-mail consultation trying to figure out how to "fix" her PCs.

She also tends to have various cool abilities and then forgets about them in game or doesnt know how to use them.

Note that it is the player who has the initial frustrations, not me or the other players. Thus I now take any PC she brings me and say "Yes, its fine. But can you play it?" I think its starting to work. She is currently playing a somewhat awkward but charming warlock with a high CHA and a low WIS. He charms the tavern wenches, but tends to let one of the other players handle negotiations.

Having said that there are several quirky PCs I want to try out but haven't had the chance:

For Planescape: Shadrack the Hellforged: Warforged Warlock (N) around 6th level with a mute gnome artificer co-hort. Shad is actually the reincarnation of a former servant of a demon lord who finds himself in his current form due to some questionable wording in a contract about immortality and eternal service. The gnome is actually a cultist, as are all of his other 'followers', of the demon lord trying to bring him back around the evil.

For a ship based Eberron game: "Haunt" an Aerenal Elf Dread Necromancer. He never gives his real name,nor indeed says much at all. He is an outcast, possibly a heretic, from one of the noble houses of Aerenal. He is guant to the point of being skeletal,but unusually tough - like he is already being preserved. He keeps his head shaved and paints on it, and his face, a skull and necromantic symbols - the latter of which also trail down his arms and legs. His ears, eye brows, and one nostril are pierced and he wears in them jewelery he has carved from the bones of small creatures he catches and kills. He often gives similar items to those he likes and is, in a lot of ways, very kind in a creppy sort of way. I picture him as part Queequeg and part Spock.

And one I have played:
Fidious ap Gaerth: A heretical angel/ancestor worshiping Paladin from a disgraced order dedicated to wiping out the black dragon that defeated them long ago. He was dirty and unkempt, rarely bathed, and prefered to sleep on the ground. He drank a lot and could, at need, cuss a blue streak. He was tweaked a bit and had lost Kn(nobility) and Diplomacy for Intimidate and Survival. He also had a celestial hound, his childhood pet who had died defending his home from the Order's rivals come back to life, rather than a mount. He was very dedicated to his Code, but I had worked out his Code in detail with the GM before the game started, and very LG - he was not, however, very shiny, nor was he like any of the NPC paladins in the game.

EDIT: Oh, I too have wanted to play a member of an traditionally evil race gone Paladin. But in my case it was going to be a Goblin Paladin with a Celestial Dire Bat and Ranged Smite.

 

[Byrons_Ghost]

It's for an upcoming game of Mage: the Awakening (not the PbP I'm running on this board, if my players there are reading), so I initially suggested he spend merits on a Sleepwalker Retainer--a non-mage character who can witness spells without ruining them. It's more the latter thing, the sudden shift in persona, that he's after. Given the darker, more roleplay-heavy tone of Mage, I think playing a character who is that deeply unstable would be a huge liability for the Cabal as they try to make a name for themselves in the local Consilium.

Tell him that if he's MPD, you as GM get to control his other personality, as well as switchovers and blackouts.

Then just make the other personality his avatar.

 

[howandwhy99]

Let him do it.

I think this is a matter of openmindedness. Obviously your player is enthused to play this type of character. And as long as it doesn't detract from the game / ruin the enjoyment of the other players, then make it work for him.

Honestly, I don't see how you cannot. Personality is not covered under the game rules for PCs. He can play his character with multiple personalities without approval. But it's like any kind of play that bothers other players (e.g. PvP), it should be addressed out of game as an unfun way to play the game for that group.

Is it really so horrible someone plays a PC with MPD in your world? If you have a tone your asking the players to hold to, maybe he can alter his concept to fit?

 

[The Ghost]

Let's see, my most recent characters include...

... a Dragonborn paladin who marks his foes with his own semi-divine semen (Sir Yatagan Fracas).

This would get a big "no" at my table. I mean a dragonborn paladin is just too weird.

... a ninja-like merchant/priest armed with a lethal pointed stick (Meritage Shiraz).

... a mystical martial artist and Communist apparatchik in the employ of the People's Revolutionary Army of Zu Mountain (Cloud Strike).

Now, these two are pretty cool and I would have zero problems with. I may have to steal the communist idea for a future character.

It comes down to does the character concept fit the game world concept. Some games are anything goes and I allow them to explore ideas to their hearts content. Other times I run very Tolkien-like games and will restrict ideas so long as they fit.

 

[Hella_Tellah]

Let him do it.

I think this is a matter of openmindedness. Obviously your player is enthused to play this type of character. And as long as it doesn't detract from the game / ruin the enjoyment of the other players, then make it work for him.

Honestly, I don't see how you cannot. Personality is not covered under the game rules for PCs. He can play his character with multiple personalities without approval. But it's like any kind of play that bothers other players (e.g. PvP), it should be addressed out of game as an unfun way to play the game for that group.

Is it really so horrible someone plays a PC with MPD in your world? If you have a tone your asking the players to hold to, maybe he can alter his concept to fit?

I run Mage: the Awakening, so yes, personality is covered under game rules for PCs. And I've let him play a character with MPD before--he's currently playing one in another game, in fact, and that's a major reason why I don't want this new character for my Mage game. The character in that game single-handedly changed the tone of the game from "Victorian horror full of dread and intrigue" to "I try to charm the squirrel, because this personality is so random!" I adapted, and so the game has more light-hearted, goofy moments he engages in while the rest of the group goes about the business of being monster hunters in Victorian London.

Really, it's a matter of tone. Specifically, he wants his character to be the result of a magical accident in which a brother and sister were fused together in one body, and the guy becomes his sister at night. Yeah, it's a new take on MPD, and it would be pretty good for a Beer and Pretzels D&D game, but Mage just isn't that game. It's a game of modern horror, in which fairly normal human beings learn that there is an invisible world around them and become corrupted by their own hubris. I mean, can you think of a way to put that idea into the horror genre?

To me, it's like coming to a game of Call of Cthulhu with a character who wants to dual-wield katanas and wear a trench coat. Yeah, you can make the rules do that--but it's completely missing the point of Call of Cthulhu. In any game, there are some ideas that are just too far outside the tone of the game.