- Averted in Dan and Mab's Furry Adventures: Dan seems to find thinking about his half-sister in a sexual way as squicktastic as the average troper.
- Better Days and Badly Drawn Kitties, 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 dramatically, while BDK used it as a Crosses the Line Twice Running Gag.
- 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 Relationship Sue
- While BDK has rebooted entirely multiple times, removing Fisk.
- Another of Jay Naylor's characters, Lynne, who has appeared a few times in Original Life, 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 Massive Multiplayer Crossover fan web comic Grim Tales from Down Below 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 Axe-Crazy levels as indicated by this late strip. Although, she is Not Herself there. Afterwards 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 Two Girl Romantic Friendship until Mimi shows up, arouses Minnie's jealousy and just plain arouses Junior.
- In Polkout it's the reason Polkster wants an older sister. TOTALLY NSFW.
- This Loserz strip mentions Chris and Claire Redfield having such a relationship.
- Powerpuff Girls Doujinshi takes the mild vibe between Dexter and Dee Dee mentioned below and runs with it.
- Concession has Rick and Kate (who are also a womanizing drug dealer and a pedophile respectively), plus 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
- NSFW Comix has Cuthwald and his sister. Averted at first, but played straight after he was rescued from being cremated at his funeral.
- In ''Fey Winds, two members of Sigurd's Minionz, Hansel and Gretel, apply.Sidney: Are you two married or brother and sister!?Hansel and Gretel: Yes!
- In Juvenile Diversion, the reveal that Julie is Jason's half-sister freaks him out, due to his feelings for her (and the fact that she slept with him, and might have had sex with him if not for the third wheel).
- 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.
- This Studs Up comic has two people discussing this trope as an analogy to being a Spurs fan. They almost got to the logical conclusion before Squick sets in.
- Tower of God has Koon, a Blue Blood who is rumored to be in love with his half-sister Maria.
- This is a key part for one of Butterfly's slaves in 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 Fruit Incest make no efforts to hide their relationship from the audience, to the point that their cousins are more visibly squicked by their Sickeningly Sweethearts status than the actual incest part.
- Rice Boy has a rather... uncomfortable sequence where Golgo, increasingly unstable and depressed, has sex with his apparent sister with their facial expressions implying that this isn't the first time. And unlike some examples, he really doesn't seem to enjoy it. Subverted as we later learn Golgo is a Searcher, meaning that she isn't really his sister at least not in the conventional sense (if she was she'd be over 3,000 years old by the time of the story). Somehow this reveal doesn't make the above scene any less unsettling.
- Touched on in Girl Genius - Word of God says that Gil and Zeetha are fraternal twins separated at a young age - which makes the scene where Gil walks around the room naked with Zeetha watching appreciatively, until she points out that he's not wearing any pants, actually kind of squicky.
- Megaman and Roll is maybe this in Megamanspritecomic. Megaman seems unsure himself, but certainly doesn't seem to mind it.
- The The Loud House spanish web comic Cueva del Caos is built around this trope, with Lincoln and Lynn getting into a relationship after coming across a secret room in their basement and Lincoln having affairs with Luna and Leni.
Brother Sister Incest / Web Comics