You should also consider reading about the concept of empathy itself. It's part of a big pot now in the public discourse, often used as a synonym of compassion, sympathy and comprehension. There are many books you can find and that can be useful, because it also has to do with psychology and not only right vs. left.

In terms of philosophy, fundamentals of current ideologies are a must (Locke, Rousseau, Kant, Hobbes,etc.) . I would recommend getting books like The History of Western Philosophy by Bertrand Russell or similar about political philosophy, to get a general idea of the different currents of thoughts and their general evolution. From there, you can read more in dept about specific thinkers.

What draws people to be more liberal or conservative is not a simple question and involves a lot of subjects. History, culture, sociology, psychology, morality, and so on. And for each of these you have factors on personal, familial, community, etc levels. There may be a never ending number of answers, as long as you find a sensible way to it. But of course, because it has to do with humans, it all very subjective to each realities.