These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: The Rocky Horror Picture Show
Adaptation Displacement: In America at least, hardly anyone has heard of the Musical/Stageshow. However it's pretty popular in the UK.
Alternative Character Interpretation: Depending on which fanfic you read, Dr. Frank N Furter is either A.) An abusive, psychotic, heartless jerk who only manipulates and hurts (both physically and emotionally) other people for his own personal amusement or B.) A misunderstood person who only acts the way he does due to some mysterious past tragedy.
Likewise, are Riff Raff & Magenta an evil brother/sister duo plotting Frank's downfall, or are they merely the victims of Frank's abuse and their actions are completely justified? Fanfics will vary greatly on the answer.
There are also plenty of fics where Columbia's personality ranges from bubbly and full of energy all the time, to always in tears and constantly depressed. Fan fic writers can't seem to make their minds up.
The only thing that could keep Hot Patootie - Bless My Soul from being a BLAM is the fact that the dinner scene calls back to it. With little or no warning, Meat Loaf rides out of a walk-in freezer on a motorcycle, sings a song, and gets murdered. That's about as BLAM-tastic as it can get.
Subverted with Eddie, since it ends up being pretty plot relevant.
In the original play, Eddie is mentioned by Columbia before Riff & Magenta (and the Phantoms) else tells them to keep quiet...Which foreshadows Eddie's inevitable appearance, musical number, and death. However, this foreshadowing (for some reason) was cut from the film causing Eddie's appearance and musical number to be totally out-of-nowhere. It's a a bizarre case of the character's scene being a BLAM, yet having the character being important to the plot.
What's worse is that a lot of these fanfics end up having the Mary Sue "love interest" causing Frank to change his "evil ways" almost immediately due to The Power of Love. Yes, the Relationship Sue is able to make Frank give up his lustful ways and settle down with one person.
Sympathetic Sue: Seriously, at least 73% of all Rocky Horror fanfics try to make Riff Raff and Magenta far more pitiful than they are in the film. Yes, the same Riff Raff and Magenta who kill Rocky, Frank, and Columbia out of pure spite.
In the play, Frank was the only one killed out of spite. Columbia dove in front of the first shot, while Rocky attempted to attack Riff in his grief. And in the film, Columbia is more killed by accident than out of spite like Frank and Rocky are.
Likewise, there are quite a few fanfics that portray Frank in the same way. Um, since when are we supposed to feel sorry for the guy who tricked two innocent people into having sex with him, brutally murdered a guy from whom he removed half a brain (said half-of-brain was used to make Rocky, BTW) and then tricked said people he had sex with into eating the remains of the guy he murdered? The only aspect of Frank that anyone should feel sympathy towards is the fact that he's batshit insane.
It's likely due to the fact that Frank's final song, "I'm Going Home", is a very desperate attempt to get people to feel sorry for him. The fact that it doesn't work and he gets killed anyway speaks volumes about the character.
Too Soon: In regards to Audience Participation. Many older callbacks get updated references but otherwise remain the same. For example, when Riff-Raff shows Brad and Janet the skeleton near the start of the film, it's customary to shout out "SHOW US" and the name of whatever celebrity has most recently died. Bonus points if it's someone people really liked, especially if they had an early or especially tragic death.
The Woobie: Poor Rocky, who appears to be only slightly smarter than your average house pet, goes through a lot of grief in one night without having any idea why. Most fans sympathize very strongly with Columbia, who really gets treated like dirt.