Why the desire for a passive dottyback?
There are a lot of fairy wrasses, basslets, and gobies with similar body shapes and behavior. I'd think about other families that may fill that role that a dottyback would serve in your aquarium.
I've heard some people keep dottybacks as utilitarian SPS pest eating fish. Springers Damsels are suspected to eat flatworms and or red bugs as much or more so than dottybacks, and they are quite agreeable with other fish. If you make the mistake of adding more damsels in after your first round of springers, then they can get a little feisty.
For whatever its worth, our orchid dottyback is the shyest fish in our tank. Aggressiveness is going to depend on your definition of "aggressiveness," tank mates, availability of food and hiding places, and the individual fish.
Maybe it would be worth researching what you can do to minimize any dottybacks aggression, rather than looking for a species which is generally not known to be aggressive and hoping the individual you get fits the pattern.