BrightBlueInk: I just took out this example:
* To a certain extent, Rosette and Joshua in ''{{ChrnoCrusade}}''. And ''of course'' Chrno and Ion.
For two reasons: (1) I don't know if Rosette and Joshua really since it's not really "taken to an extreme" (maybe when Joshua's under the influence of the horns, which ''might'' count...I'm not sure), and (2) Chrono and Aion were already in an example two lines above this one.
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InvaderSin: It occurs to me that there might be a subtrope here in which you have two siblings (sisters in the examples I know of, but not necessarily always) in which the older one is immature, lazy, and ditzy, and the younger one is mature, sensible, responsible, and hardworking. The two examples I've encountered so far are Tenma and Yakumo in ''SchoolRumble'', and Yui and Ui in ''K-On!'' It's even lampshaded in the latter, as the other characters comment that the situation is like something in a TV drama.