Characterization IV: Defining Details

I could probably sell this like a salespony if I wanted to, but I don't really want to. Mostly because I would never, ever make a good salespony. I mean, imagine me trying to sell you something in a store. "Uh. Hi? Actually I think you need a size bigger. Why? Because your hoof is too fat. No, I'm not saying you're fat, that you have fat hooves. Well you do. Not really, you're actually pretty thin. You might want to go to a doctor about that. About what? About being built like a pyramid. Normal ponies don't have fat hooves, big legs, and tiny little bodies, sir. Oh, you're a mare? Well. You look like a sir. Sir."
Yeah. Yeah.
Okay. So defining details or characteristics. Every character has them. Why? Because every person has them. Even those ponies who just seem to stand around in the background has something that helps make them them. And what that specific thing is varies from pony-to-pony... person-to-person, really, because almost everything literally has something about it that helps set it apart.
In writing, this is a useful tool, and you can be either very subtle with it, or very clear. You can say that "Mr Dump would always smoke a cigarette on the corner," or you can say "The pony took the object with his left hoof," and reiterate use of the left hoof. Implying, thus, that he's left-hooved, which could be an important detail later on, could be used as a red herring, or could be... well. Just there. Sometimes things are just there; it's something important not to forget when writing, especially about things like this.
So let's look at that as the... second, I guess it technically is, point. A defining characteristic can be defining without necessarily having to mean anything. Maybe a certain character, for example, has a big ugly scar on his side, and that's what first defines him when he walks into a room. Well, that doesn't mean that the scar is his entire character. Maybe it's just there, to help draw initial attention to him, and then is never really mentioned again. You don't have to discuss it or give it some giant backstory, and even if you do, then it doesn't have to be "he was attacked by demons and got the scar while killing twenty of them with his terrible sword Ickamakijetsu!" It could be... "His wife demanded waffles this morning, and while this loving and affectionate husband was making them on the griddle, said wife decided it would be great to tackle him into the freaking counter."
Yes I'm looking at you Luna. I'm not going to get killed by a dragon or a monster or some terrible force of evil. I'm going to get killed trying to make you something nice for breakfast and you decide to give me a very ill-timed tackle-hug right into the stove.
Also, notice what I did up there? While I discussed the defining characteristic, in both instances I used it as a bridge to get into other things that define him or can now be implied about him. In the one example you get, he has a sword named... I can't type that again... he's apparently good with it, and he fights demons. In the other you get, he's married, he's a wonderful husband, his wife is evil.
Affectionate, but evil.
Physical things that define characters are easier and often more striking than the intangible: I might say someone is generous, for example, but unless I give an example of his generosity, it could mean anything from he dropped a bit in a tip jar once to he gave away his yacht to a foal he'd never met to help him fulfill his dreams of sailing the world. But if I say "he's tall and broad shouldered," that's more specific, and those things are a little less debatable. You can argue about how tall, or how broad shouldered, but either way it's not nearly as up to your opinion as the other example.
It's not to say that an intangible thing can't be the most striking about someone, but a lot of it comes in the presentation and reiteration. "His cold gaze," for example. If that's the defining characteristic you settle on, let's say, then you have to make sure you repeat it when necessary, and match the character's other traits to this specific characteristic, because also helps set up a personality descriptor. Most happy cheery people don't have cold eyes, after all.
But I'll get into defining personality for characters next week. That's much trickier than just giving your character something that stands out, because... that something can be anything. Personalities, on the other hoof, they tend to require a few more specific details, and things to go in proper order. Otherwise, you end up with me and Luna. Or Twilight Sparkle.

~Scrivener Blooms