There’s always Fred and George Weasley. And Voldemort and Harry, which is just “WTH” on many levels.
You’re right of course - but the audience doesn’t find that out for a while.
Anybody/Lockhart is creepy, really. Voldemort does vile things in order to rule the world and live forever. Lockhart does (somewhat less) vile things to get on TV.
I was very lucky. That was the only episode of the fourth season I missed in the first run, so though I knew it had happened I got to miss the actual fucking. By the time I saw it I knew that was the the Cordelia I knew and loved.
I’m glad I spoilered my find if this is the worst you’ve found.
I’ve seen Harry Potter pairings that I severely hope were a joke (Ron/giant squid is the classic one).
I’ve seen Digimon fics that weren’t jokes, that made me fear my generation (underage non-consensual, homosexual, incest. Sometimes with bestiality, depending on how you consider the Digimon). I’m sure there are Pokemon fics that are worse. I’ve seen Charizard/Ash, but at least it was consensual. I refuse to think about the size differences.
Data/Wesley Crusher
Dobby/Hermoine (remember S.P.E.W.?)
D’Argo/Rigel
Lord Percy/Baldrick
I know very little of Digimon or Pokemon, and I believe I shall retain my innocence. Sometimes ignorance should be embraced rather than battled.
Neil Gaiman wrote a short story called The Problem with Susan which 'shipped Aslan and the Witch.
No underage there, but still quite successfully icky.
Gods of Earth, Sea, Air, & New Jersey! How blatant did I have to be in asking not to be reminded of that ? 
Nah, I’m sure there are much weirder ones I’m blocking out. In regards to your pairing…yeah, that’s pretty bad.
Ah yeah, but you know, for the folks playing along at home who want to have to bleach their eyeballs.
Because nothing’s better on a Saturday night than a good hydrogen peroxide eye wash.
It’s too late to rationalize it. I have already released my
::checks schedule to see which improbable assassins I’m using this week ::
sulfuric-acid-spitting turkeys and commanded them to seek out and discipline you.
I remember a discussion of Heroes in the first season where some people noted that the chemistry between Nathan and Peter was so strong that some might consider them a slash pairing.
QFT. Some days I wish I could be as innocent as everyone thinks I am.
Considering the way that family gets around, it’s conceivable that every pairing and potential pairing on the show is incestuous.
Fear not. After the conquest I shall have your memories removed, as you know enough of my weaknesses to be a danger but I cannot bear to murder a 'Cats fan. Once the hippocampus-scrambler is done with you, you will believe yourself to be Wiley Kit.
In the tradition of Bob and Carol and Ted and Alice,
Fred and Ethel and Lucy and Ricky
Dry County: Grandpa Walton and the Baldwin Sisters (“70 is a long time to wait to lose your virginity, but sometimes it’s worth it…”)
Stefan Urquelle and Steve Urkel
Robotic kiddie porn with Small Wonder
Laura Ingalls and Mr. Edwards (“now that was a half-pint”)
Fool of a Took! It is pointless to do slash with Little House on the Prairie! They have CLOWN RAPE as it is!
Absolutely not true. That clown was not raped. (And the girl was practically asking for it.)
Complete total aside: I remember when that episode aired. At school the next day we were all saying “So did she die or not?”, because it actually didn’t make it clear.