Someone is into OP or whoever is in gold, at least for now. Even if you don't find it cool, flatter to keep conversation and interest. It could be genuine as in finding interest in anything your crush is into interesting, or be just practical.

Also, people are attractive/interesting when they speak about stuff they're passionate about. Lots of people will listen to you blab on about something they know nothing about or care nothing about if you interest them in your delivery.