Interested in particle physics and all the stuff involved in that. Background is electrical engineering which I got into because of this interest. Coolest thing I got out of that choice was a class in quantum dynamics as a core class for specializing in electronic devices. Physics stack exchange has a lot of great question/answers that help me think through some interesting questions like how fast a photon is with respect to another photon. I am still surprised by some of the things I learn.
Please note that as an amateur, answers don't mean much if I don't know the source or preferably the specific experiment I can look up.