Is there any sibling relationship that wouldn't instantly become better if they started fucking eachother?

of course she doesn't want to at first. In all the doujin I've read it has to start as rape adn she'll give in within 5 pages

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That's not because she's my sister though, it's because she's 3DPD, not cute at all. If my sister was cute I would probably want to fuck her.

She's like kirino and I don't think she has brother issues. Since she's already a bitch I guess chances are low.
She doesn't want to though