What sounds in names show the personality of a character?

I need to rename a character, because the name never quite fit their personality. I need names for other characters as well, but the renaming is my primary concern. Now, what I need are sounds that enhance certain personality and character traits. Salazar, for example, sounds regal, but perhaps not the kindest royal. I'm not sure which sounds in it, however, give me that impression. Is it prior usage?

For renaming my character, I'll give you a brief summary. They are a character I've had for about three years now, fleshing them out. Unfortunately, the brief overview I will give shant do them justice. They are a genderless immortal, strong but a side character, only playing antagonist as a lead role in the few stories thay take lead roles in. They are like a mix between the Cheshire Cat and the Mad Hatter, appearing in odd places and when called, and a tad manic. They like to make deals, even if they can lose them, but not if it is a deffinite loss for either side.

For the other characters, I need some sounds that fit a cowardly boy, a sweet girl, and a pair of emotionless twins.

If you can supply, perhaps, names, I could also find some sounds that may fit as well. It doesn't mater what language the names or sounds are from. Any help is most appreciated.