It really depends on how long the wrasse has been in your tank, and how big it is. I know people that have had success with keeping multiple wrasses (one in particular had a great combo with a lunare and a yellow, great color combo too) but he acclimated them all around the same time. If you really want another wrasse, I'd go with a more aggressive one to match the already bold personality of the lunare. I'd definately rule out any wrasses that have a really hard time getting used to a tank, like fairy wrasses (who tend to be really shy when first introduced). Small wrasses are also gone.