This is a Wraith essay for White Wolf's World of Darkness. At the core of each Passion is a single emotion. Inspiring that emotion in others, or finding others who feel it, further fuels the character. I decided to start from the beginning. I began with the textbook from a Human Emotions class - The Psychology and Biology of Emotion, by Robert Plutchik.
Many psychologists subscribe to the notion that there is a very limited set of actual emotions.
Love is very occasionally included, but love is usually considered to be a much more complex state than a simple emotion. Still, the six above seem to be the most common, in my albeit brief study of the subject. Below is a list of emotions I have culled from a number of sources. Then look at the list if you're having trouble coming up with just the right word for the emotion that goes with the Passion. I don't promise that all of these will be appropriate for Passions, by the way.