As the term “… one of them” keeps popping up at Welltun Cares Presents these days (all of two times so far!) let’s have an essay where we look at this thing in depth.
So far, the standard definition has been the following: “A boy protagonist apparently created to appeal to boys by being as obnoxious as possible.” Let’s further stretch this to the following:
A protagonist who is… one of them (from here referred to as an OOT Pro) is usually a male who is a hero by default He is rude, obnoxious and always, always in need of “learning better.” His opinions are often if not always wrong, and while he might think himself competent, it’s usually due to a full head. He is usually paired with a letter perfect female who is there primarily to a.) put the OOT Pro in his place, b.) be secretly be in love with the OOT Pro, and c.) get herself kidnapped in order to prove the OOT Pro a real hero.
The OOT Pro might have worked in, say, a single story, but is almost always put in a series,. Thus anything he might have “learned better” about will be forgotten by the next episode/book/installment in order to maintain the status quo.
Rule of thumb is that the OOT Pro’s main antagonist is more likable than he is, even if the bad guy is a monomaniacal dictator. If you find yourself rooting for the villain to kill the hero, the hero may well be an OOT Pro.
Very, very close to an Idiot Hero, except the OOT Pro is competent right up to the point where the writer wants to prove Girls Are as Good/Better than Boys.
Bear in mind that when protagonist used above, it is in general meant as “the character the story is about.” If the story is an ensemble piece with more than one male, the male in question can often be ignored as just a jerk. A lot of this is a sort of Milage May Vary type of situation.