I feel that the named always gets to choose what they are called, whether it's a nick, or a long version or an honorific. Unless, of course, it's an elderly person or someone like that, in which case it's more polite to let it slide.

I always ask new employees what they want to be called. Once in a while they HAVE NO PREFERENCE. You don't care if you are called David or Dave? WTF? WHAT IS YOUR NAME?

Hrm. I'm unsure what my ish is.

Aw man, I'm sorry Cash.

Once in a while they HAVE NO PREFERENCE.

...I don't care if you call me (realname), meara, or Indy (drag name). I answer to all three. I like all three (well, OK, I like Indy and meara better, but I answer to realname a little easier because it's so uncommon...)

You don't care if you are called David or Dave? WTF? WHAT IS YOUR NAME?

Seriously! You're Deb, Debbie, Deborah? Can I call you Suzie? WHAT IS THIS MADNESS?? WHERE DOES IT STOP??

I have carefully called my BFF's husband and brother (2 different people) Billy and Philip, which is what she calls them. Turns out Billy goes by Bill and Philip "has no preference". I now work with Philip and everyone except me calls him Phil.

I call my sister Al or Ali, but I don't think people who know her outside of family get to call her that. Anyhow, as she saddled me with MY name, she can suck it if she doesn't like it.

my BFF's husband and brother (2 different people)

Good.

You know, it's probably a, "but this is the name on the credits!" thing.

but this is the name on the credits!

That's entirely legally driven, though.