Make a point to research or engage with their interests in your free time. If they keep talking about a comic book or podcast they are into, or they recommend a recipe or product, check it out after your conversation. You might discover that it’s not really your thing, which is fine—you don’t have to join their fandom to further the friendship. Even saying something like, “I looked up that wild Wikipedia entry you mentioned the other day and—WOW!” communicates “I am listening to you and I am interested in you.”
