Quote from BioWizard >>

 If your DM hated it, they would should have said “no.” They likely can’t hate it very much since they agreed to your character.

 

Well... maybe.

Many DMs don't like saying no to a player if the player is really excited about an idea and really wants to do it. If we feel we can "live with it" many of us will put up with it even if, fully given our druthers, we'd not have allowed it. There are a several rules options I allow in my campaign that if I'm being honest, I really don't like, and I'd rather not use... but one of my players asked for it, and I have said yes because I can stomach it, even if I'd really rather not. As I said above, many of us are self-sacrificing that way.

IMO, as a player, one of your jobs (and you don't really have all that many as a player, compared the the jobs a DM has to do) is to try not to paint the DM into a corner where the DM has to say yes to something he or she really doesn't want, to avoid making you unhappy. That's why I said, always give the DM an out... always be clear that this is a cool off-beat idea that you have but it's OK for the DM to say no -- you won't be upset. And you need to actually not be upset. I mean -- basically what I'm saying is people need to be grown ups and cooperate here, rather than wanting it their way or the highway.

 If one can “put up with it” then that means they don’t “hate” it. They may not like it very much, but to me “hate it” implies an inability to put with it. 🤷‍♂️

Well, I did say, that very few DMs actually "hate" a concept. Hate is a pretty strong word.

But you can put up with things as a DM that still make you pretty unhappy. And in the long run this is probably bad news for a campaign, since an unhappy DM is going to eventually lead to unhappy players. 

I say this from experience... more in Champions, which is a far more open-ended system without classes or races or any of that stuff. Several times I allowed PC concepts in that game that I really didn't like, and my gut told me not to, but the player had his heart set on it, and I didn't want to ruin the player's fun. Dealing with those characters became (as I should have known and to be honest did know) a major chore and made the GMing experience a lot less fun for me than it would have been without that character concept or power concept or framework. (I am looking right at you, Variable Power Pool!).

As a GM, I have allowed players to do many things, large and small, after my first instinct was to say "no," because I want them to have fun. And as I said, I am to some degree willing to sacrifice my own fun, or do a little more work than I normally should, if I think my players will have more fun as a result.

That is exactly the reason that PC races are restricted by geography in my campaign world. My experience has taught me that sometimes, “no” really is the best answer. My solution lets me say:

“None of that race live in that area, and if they were to have traveled from a distant land, they wouldn’t still be 1st level. If you want to play as Race X, you will have to wait until the party is of an appropriate level to accommodate such a character in the party, and then you can switch characters if you like.”

By the time the party is mid tier the player is usually invested in their first character and don’t want to switch. And if they do, at least I have some options on how to handle things.

That being said, Couatl is a hard “no” in my campaign setting as a PC race. I mean, their myth originated as an IRL Aztec god. I play the gods and godlike entities, the Players play PCs.

I generally agree (especially on the hard no for Couatls). For my current campaign, I gave a list (that included a lot of races... most of the default ones and then also several of the newer optional ones) and said, "Please pick from this list; do not choose something not on the list." I ended up with a human, a dwarf, a gnome, and an Aarakocra. (I had purposely made the Aarakocra race somewhat attractive in the hope someone would pick them, because they just seem cool to me.)

Quote from BioWizard >>

I generally agree (especially on the hard no for Couatls). For my current campaign, I gave a list (that included a lot of races... most of the default ones and then also several of the newer optional ones) and said, "Please pick from this list; do not choose something not on the list." I ended up with a human, a dwarf, a gnome, and an Aarakocra. (I had purposely made the Aarakocra race somewhat attractive in the hope someone would pick them, because they just seem cool to me.)

 I also allow my own nonstandard races as well. Half-Dwarf/Gnome/Goblin/Hobgoblin/Ogre. And I have allowed Orcs, Goblins, and Hobgoblins as PC races since the ‘90s. Most folks can find something to play. I have one player (another DM in our group) who will always specifically ask to play something after I have excluded it. As soon as I say “these are the disallowed races” the man feels compelled to try one. Wasn’t interested until he heard they were banned. Even he settled on something from my list... eventually.... And then switched characters by 3rd level. (That’s usually how I end up with party NPCs. I don’t create them, I just inherit them from people who switch characters.)

I think every group has the player who only wants to play something because he or she was told it's the only thing disallowed.

For the record, Nightcrawler uses the epee, not the rapier

Another option is either to check out the existing homebrew or create the homebrew yourself.  It's actually fairly easy to have a monstrous race species fall in line with existing races  species without being OP; I've done several myself as I was looking at running a campaign based on monsters who are trying to redeem themselves and worked with my players on fleshing them out.

Here's two examples but they're not published so I'm not sure they'll render:
- Illithid: The Illithid Species for Dungeons & Dragons (D&D) Fifth Edition (5e) - D&D Beyond (dndbeyond.com)

- Shadow Demon: The Shadow Demon Species for Dungeons & Dragons (D&D) Fifth Edition (5e) - D&D Beyond (dndbeyond.com)

For me, as a DM, anything is possible.

Firstly, I have a fairly solid rule that PCs are humanoid in shape. The race may be Fey or Construct but being a beholder, straight, is not going to fly. However, being a Beholder who was tricked into a humanoid form, with spells flavoured as the eye beams and an attitude to suit the beholder will work really well. Taking a race like, say, Aasimar for gaining a flying speed as you level up is quite thematic.

Secondly, reflavour before you rewrite, always. For example, if your player wants to make a nightcrawler character, then there are umpteen options to help them to do it. They can be a Shadar-kai, to get a teleportation ability off the bat - reflavour their appearance as blue, but mechanically, they're shadar-kai. Then they can take the Fey Touched feat when they hit level 4, giving them misty step for additional teleports. Then take a class like Gloomstalker Ranger for stealth attacking, the flurry ability at level 11, and invisibility in the dark, which can be reflavoured as teleporting everywhere so people don't know where you are.

Having a character which teleports everywhere all the time would be overpowered unless it were heavily downsided, EG "you can teleport up to 30ft, cannot pass through solid material, have to see where you are going, it costs an action, and it uses your movement", in which case it's still powerful but not so powerful as multiple teleportations.