That Blake’s 7 fandom was materially better before the show aired in the States. They had gone through the painful sorting out of characters and characteristics and relationships and were developing these really interesting themes of psychological trauma and manipulation that they were beginning to explore - it was really interesting and the themes were fascinating. Them the show aired in the States, they went wild over Avon and all the stories and themes starting revolving around him. I don’t mind him as a character; I do mind his character taking over all of fandom. It’s sort of like if all the Harry Potter stories suddenly and inexplicably became Ron-centric; it’s not necessarily wrong, but it’s weird and people who liked other characters got left out in the cold, and some of us still resent that.

As an aside, when Blake’s 7 fandom split up, that too was fascinating. As was usual in those days, there was a pro-slash contingent and an anti-slash contingent. When B7 fandom split up, all of the pro-slash fans went into Robin of Sherwood fandom, and all the anti-slash fans went into The Professionals fandom. The problem being that RoS was almost exclusively gen and Pros was almost exclusively slash. It was very weird.

What else? That the second season of War of the Worlds should’ve been an entirely different series: the people who loved season 1 were never going to like season 2; and people who had tuned in and disliked the series during season 1 weren’t going to Even try season 2.

That Krycek became such a big character on The X-Files due to one woman who saw his potential and kept talking about it to her friends, many of whom were popular/prolific fannish authors and artists. She convinced some of them (there was incredulity and resistance at first) but it gathered steam, Chris Carter was flummoxed but rolled with it, and here we are.

That the main follow-on series for Highlander: the Series should’ve been The Methos Chronicles and that one’s not even up for debate.

That the final episode of Miami Vice is a masterpiece, particularly with the echoes and parallels to the first episode - and that the show itself took a major downturn the moment they decided to kill off their comic relief characters. That having God in the final episode of Quantum Leap (the original) being played by an actor who was also in the first episode of the series made it much more interesting. That if you were ever interested in Space: 1999, the “Message from Moonbase Alpha” short has some really interesting implications.

That Space Rangers and Moon Over Miami were cut off entirely too early. That Quark is funny as hell for a science fiction fan of my generation, even if it’s extremely dated now. Similarly, The Secret Adventures of Jules Verne was hella fun and should’ve lasted much longer (though Michael Praed’s Shatner-esque line deliveries were exceptionally annoying at times!). That the Sonny Steel grave arc is majorly under-represented in Wiseguy fiction.

Almost certainly others, but those are the ones that came to mind.