Like badly built houses, when your characters suffer from faults in their very foundation they can get by just fine with good weather. But when conditions turn ugly, their weaknesses begin to show and the drama starts to happen.
To make a really great character, think like a bad contractor:
Get off to a bad start. Because logline models stress the importance of the protagonist having a flaw, protags become “jaded law professors” and “uptight dental hygienists.” Those descriptions are underpowered. Flaws aren’t decorations you add on after the fact; they come from where you choose to dig the foundation. Pick some uneven, shifting ground with drainage problems for prime flaw creation.
Build impractically. Spec characters turn interesting when they are ill-prepared for the inciting incident. Don’t build a character up on pilings if your inciting incident is a flash flood. Increase the drama by putting everything important down in the basement so that when the waters begin to rise, it’s a big, immediate, catastrophic problem.
Make the living spaces dark and cramped. Confine your building to a small footprint, a single circumstance from which all the troubles flow. Don’t be tempted to add on explanations. It costs in clarity and page space to build extra personality flaws (as with extra rooms in a house) to move the plot along. A restricted space creates layers, as an oyster creates a pearl by an inability to escape constant irritation.
