Quote Originally Posted by lelouch View Post
Who writes this, and WHY? I just don't understand the point. It's not cool or fun to watch, it's gross and weird.
It's very cool and fun to watch. It's awesome and it works.

The point is that you get a never-ending harem, but at the same time you get the full-blown clingy relationship. Neither terminates because the harem can't beat the sister, while the sister is invalid. You get the never-ending best of both worlds.

And really, if you get along with your sister then isn't she like the best childhood friend you could ever have? Characters get all flustered about sharing a roof with the other sex, so anime logic is that if they live like this they'd totally fuck.