I think the worse is the lilac of Lunair's eyes. Serai and Reivier look OK to me.
(I wanted to suggest to make the tongues shorter, but since they are only 4 pixels anyway, that's kind of pointless.)
But I agree with legacyblade, you can make the whole face a bit bigger downwards (just look at the height difference between the angry and the grinning Salory!

), and then you can drag the line of the mouth 1 pixel down too.
Though, to be honest, I have to add that it's kind of putting off, having smileys like that. It's a good thing first-hand, but in my opinion it should be left authentical. So if you really want to make other characters

, make it Vikon or Eshe (or maybe Petal, she has only 2 faces). It just doesn't really fit the others, given their character. The

:nairstare:

fits Lunair, the

Reiver, the

Salory... isn't that enough? It's more fun like that.
Sorry if I sound conservative (which I have to admit I am), but I just don't want to break the feeling of the good things.
