This thread reminds me: I have never supported a local team. I was born and raised near Hamburg, now I live in Hamburg, which is home of many football clubs. Most noticeable HSV and FC St. Pauli (both are in the top flight, even though St. Pauli looks like they might get relegated again this season), but I have always been a supporter of FC Bayern München since my early childhood. Pretty strange if you think about it, since Munich is about 800km away from Hamburg. Also, I have never visited a home game yet (as I've said Munich is just too far away).
When I first visited Glasgow I already knew about Rangers and Celtic, but I wasn't too interested in those. I then learned about the ONLY team in Glasgow and started supporting them. I even made it to a home game last year (against Dunfermline, which we lost 2-0 ).