This is a frequent cause for problems on TV Tropes. Square Peg, Round Trope examples tend to be a sign that a trope (or a group of Sister Tropes) has one or more underlying concepts that cover less specific situations.
When an editor wants to list an example that shares the underlying concept, but doesn't actually match the specific Trope(s), they will tend to add it to one (or more) of the pages, perhaps saying that it is "a variation" or "not a straight example". Sometimes these entries are decidedly in violation of the page's definition, making it textbook Square Peg, Round Trope. When multiple editors start using the same "variations", it is a form of Trope Decay.
Why does it happen? It's a lot easier for editors to propose (and write up) tropes of specific concepts than the more general ones that underlie them. It's often the case that a new trope was inspired by one specific example, and the troper found enough similar examples that a trope could be formed. In other cases, writers and authors want to include certain elements of the trope, but want to spice things up by downplaying it, adding new elements to it, or otherwise changing it so that it no longer fits the exact definition of our site.
Signs a trope may be suffering from Missing Supertrope Syndrome
- Word Cruft to fit examples into the definition.
- Generic name for a specialized trope.
- Multiple sister tropes without a parent trope (or index).
The simplest fix is to go to TLP, create the supertrope, and migrate any misplaced examples and wicks to the correct trope. Usually, that's all that's necessary. Depending on how far the symptoms have progressed, more drastic action might be needed. In some cases, tropes have accumulated so much misuse for their supertrope that we've had to give them the full Trope Transplant, broadening the trope to accommodate the Trope Decay and launching a new trope to salvage legitimate examples of the more narrow subtrope; this is mostly for specific tropes that have overly-general names. Other times, the narrower trope might be The Same, but More Specific, and once the supertrope is in place, the subtrope is no longer necessary and we just redirect it to the parent trope.