People have emotional baselines. Default feelings. Blueprints for all feelings to come.
Usually, these are based on feelings past.
This is not to say that there's determinism at work here. But you can understand a person very well if you manage to empathize with their emotional defaults. The places to where they go when they are not going anywhere in particular. The equilibrium awaiting perturbation.
There is no one default feeling. There's always a bunch of them, being more or less present at any given moment. Some might be frequent, others rare, but they are.
Some of my most frequent are based on being outdoors alone under an overcast sky, not quite rainy but all the more melancholy for it. Not just the one time, but many times, many ages: as a small kid, exploring the oversized mountain behind our equally oversized house; as a slightly less small kid, walking to the nearby village without telling anyone; as a school kid, not quite wanting to be social during recess; as a highschooler, deliberately getting off the bus at the wrong station in order to establish a good long distance between me and home; recently, deliberately trying to get lost in this city in order to find new places.
There is no one default feeling. But some are more frequent than others.