In its story and roleplay, The Observer is an omnipotent being with no true form, so it can change into what it wants whenever it wants, but it normally chooses the form of a rather androgynous male. It does have an animal form, as most of its kind do, which is a snake. Therefore, any human form it turns itself into will have a snake's tongue.
The Observer is nameless, so it is either known simply as 'The Observer' by most, though some prefer to call it 'Serpent' in an insulting sense.
It will trespass upon the workings of Fate and play either a Good Fate or Bad Fate so long as it is kept entertained. If, however, it grows bored of its current occupation, it will switch sides for the sake of finding something to do with no care whatsoever for the 'pieces' of the game board the Fates have made.
The observer is nonchalant about everything other than itself and its boredom. It will leave without hesitation if it becomes bored of anything.