Campari and fresh squeezed orange or satsuma juice make a mighty fine sipper
The fizz is optional. I think it lightens things up and cuts the bitter but sometimes you want things bitter, you want to take it slow. Times like those I might skip the fizz.
Satsuma Bitter Cocktail https://www.recipefiction.com/2014/02/five-minutes-of-fury-writing-prompt.html