* Averted in ''Webcomic/{{Dan and Mabs Furry Adventures}}'': Dan seems to find thinking about his half-sister in a sexual way as [[{{Squick}} squicktastic]] [[http://www.missmab.com/Comics/Vol_692.php as the average troper]].
* ''Webcomic/BetterDays'' and ''Webcomic/BadlyDrawnKitties'', which had a shared cast of characters, including twins Fisk and Lucy Black. The two comics used the sibling's special relationship in completely different ways. ''Better Days'' used the relationship [[http://www.jaynaylor.com/betterdays/archives/2004/10/chapter-10-brot-19.html dramatically]], while ''BDK'' used it as a CrossesTheLineTwice RunningGag.
** Although as ''Better Days'' progressed both characters seem to deny it happened, it slowly became a forgotten dropped storyline, and both moved on to their respective RelationshipSue
** While ''BDK'' has rebooted entirely multiple times, removing Fisk.
** Another of Jay Naylor's characters, Lynne, who has appeared a few times in ''Webcomic/OriginalLife'', frequently screws her younger brother Genwyn. Sometimes against his will, though he initiates it at least once in their porn comic. And while Lynne gives a lot of guys head Gen is one of the few who've had intercourse with her.
* In the MassiveMultiplayerCrossover [[FanWebComics fan web comic]] ''FanFic/GrimTalesFromDownBelow'' by Bleedman, Minimandy/Minnie seems to love her brother, Grim Junior, in a manner beyond what would be acceptable sibling behavior.
** Her heretofore ambiguous feelings, once made explicit, are also cranked up to AxeCrazy levels as indicated by [[http://grim.snafu-comics.com/?comic_id=107 this late strip]]. Although, she is [[NotHimself Not Herself]] there. Afterwards [[http://grim.snafu-comics.com/?comic_id=136 she doesn't seem to have given up hope]] and his response seems ambiguous. In still later strips they seem to have settled down to a heterosexual version of a TwoGirlRomanticFriendship until Mimi shows up, arouses Minnie's jealousy and just plain arouses Junior.
* In ''Webcomic/{{Polkout}}'' [[http://www.polkout.com/page156.htm it's the reason Polkster wants an older sister.]] TOTALLY {{NSFW}}.
* [[http://the-qlc.com/loserz/go/390 This]] ''Webcomic/{{Loserz}}'' strip.
* ''Webcomic/PowerpuffGirlsDoujinshi'' takes the mild vibe between [[WesternAnimation/DextersLab Dexter and Dee Dee]] mentioned below and runs with it.
* ''Webcomic/{{Concession}}'' has Rick and Kate (who are also a womanizing drug dealer and a pedophile respectively), plus [[spoiler: Joel and his dead sister Miranda, possibly, she died as a young child but is ''really'' close, you could say possessive, to her brother as a ghost]]
* ''Webcomic/NSFWComix'' has Cuthwald and his sister. Averted at first, but [[spoiler:played straight after [[NotQuiteDead he was rescued from being cremated at his funeral]].]]
* In ''Webcomic/FeyWinds, two members of [[BigBad Sigurd's]] Minionz, Hansel and Gretel, apply.
-->'''Sidney:''' Are you two married or [[VillainousIncest brother and sister]]!?
-->'''Hansel and Gretel:''' [[MathematiciansAnswer Yes!]]
* In ''Webcomic/JuvenileDiversion'', the reveal that Julie is Jason's [[spoiler:half-sister]] freaks him out, due to his feelings for her (and the fact that she slept with him).
* ''[[http://www.absolutehotsister.com/ Absolute Hot Sister]]'' is built on this trope. Ellen has gone so far as to suggest to her brother Kevin that they sleep in the same bed and take showers together.
* [[http://www.studs-up.com/2009/12/analagous-madness/ This]] ''Studs Up'' comic has two people discussing this trope as an analogy to being a [[EnglishPremierLeague Spurs]] fan. They almost got to the logical conclusion before {{Squick}} sets in.
* ''Webcomic/TowerOfGod'' has [[MagnificentBastard Koon]], a BlueBlood who is rumored to be in love with his half-sister Maria.
* This is a key part for one of Butterfly's slaves in ''Webcomic/{{Collar 6}}''. She and her sister were both married to the same man, since polygamy is okie-dokie in this world, and he thought they should engage in this. She didn't agree while her sister did. That got her shipped off to attempt unpleasant "changing" in her thinking.
* Apple and Orange from ''Webcomic/FruitIncest'' make no efforts to hide their relationship from the audience, to the point that their cousins are more visibly squicked by their SickeninglySweethearts status than the actual incest part.