No one wants to read a Miss/Mr. Perfect Mary Sue/Gary Stu, or someone whose "faults" are really just endearing quirks. But at the same time, I also know of characters who people genuinely can't stand because their flaws make them seem like assholes, incompetent, idiotic, or otherwise straight-up unlikeable. Having unlikeable characters can work in an "unreliable narrator" type of way, or for stories like Gone Girl or Dr. House. But let's just say, for the most part, that most of us in general want to have our readers actually like our characters and want to root for them, write fanfic about them, etc. Where's the line between "obnoxious for being too perfect and having no real flaws," and "obnoxious because their flaws make them unlikeable?" How do you create that ideal mix?