2 years ago I was in London the day of the League 2 Playoff Final at Wembley. I purchased tickets from Stockport FC and watched them lose to Carlisle. The experience at Wembley was cool even though it was only about 30% capacity. It was amazing to see the passion that fans have for clubs I hadn't heard of until about a month before I made my travel plans.
I follow Stockport last season and was excited they won promotion. I was excited this season when they started in amazing form and we top of league 1 for a few weeks. Now they have faded to middle of the table with about 5 draws in 6 but I still follow the table and hope they win promotion to the championship at some point.
I loved Sunderland Til I Die on Netflix a few years ago. It really gives a cool perspective on fandom and some of the history and uniqueness that promotion/relegation brings.