Fans of 'A' are more often than not very similar to Fans of 'B'.
Sports Fans are very similar to Trek fans too for example.
Talk of stats, what they did right/wrong, and what-if's... Some super-fans even dress-the-part for games/conventions, etc.
Fan Behaviors tend to be expressed in very similar ways.
Once I made the connections, I've never been able to 'not' see it.