Fantastically Indifferent

"Robo: Overall, I gotta say, you're taking this rather well.

Carl Sagan: Astronomy is a long and relentless lesson that the universe is under no obligation to match up with your expectations. Also, the alcohol helps."

- Atomic Robo and the Shadow from Beyond Time

Take a person. Something fantastic happens to or around them. He or she acknowledges that something as supernatural or as something that should be impossible, but, when people expect them to freak out, they don't. It turns out that the person in question utterly fails to react with the sense of wonder that something fantastic, unnatural or supposedly impossible would entail. This usually happens for one of two reasons:


 * 1) The person is just that calm or collected; or
 * 2) The person has seen enough of this sort of thing, maybe from the same source, that - though they recognize it IS fantastic - they got used to it enough to view it as "normal" - for them, at least. This isn't quite Seen It All because the person in question tends to be a Muggle Best Friend or some sort of normal that knows what's going on - and knows it enough not to mind anyways.

In the first case, the person is more likely to berate others for their overreaction, though not always. In the second case, the person already reacted strongly to this kind of thing a few times, if only offscreen, so they won't really mind when others do. Mind that the person does know the event is impressive or surprising - they're just too calm or too used to it to really mind. Superheroes that work in teams depend on this trope not to stare wide-eyed in the middle of a battle whenever a teammate does something.

Compare Stiff Upper Lip.

Comic

 * In Atomic Robo, both Carl Sagan and Charles Fort react rather calmly to the reality-warping machinations of an extradimensional Eldritch Abomination -- although Sagan does take a moment (and some booze) to reach this point.
 * As noted, superheroes have a tendency to do this, as well as those around them.

Literature
""I don’t want to think about this, I don’t want to talk about this. It doesn’t do us any good. We know what’s at stake. What we have to figure out is what’s our first move.""
 * Ronnie, in Anita Blake Vampire Hunter has no psychic or magic abilities and despite her job as a P.I. not a lot of contact with such things outside of her association with Anita. When the weird crap happens, though, she takes it pretty well. at least until her character derailment later in the series.
 * Also Edward from the same series. Yeah, he's an assassin who kills monsters for a living, but turning into some kind of human vampire who feeds off of sex is still pretty outside his experiences, so when Anita reveals this has happened to her, it should still be a shock, but he's more or less like "Well, that's unusual." And finding out that the vampire who are so scary that other vampires are afraid of them are after Anita, should give one pause as well. His response is basically *shrug* "Okay, so how do we kill them?"
 * Candy Quackenbush from Abarat is like this. She accepts one bizarre thing after another, just as they come because, she reasons, what else can she do? Word of God has said that he intentionally invoked this to spare readers from having to read pages and pages of freak-out scenes.
 * The Pikka birds in Hitch Hikers Guide to The Galaxy embody this trope. They're not surprised by unusual, million-to-one, you'll-never-see-that-again events, because, well, they're unusual, million-to-one, and you'll never see them again in your life, so why bother noticing? And yet, every morning, the sunrise takes them completely by surprise.
 * In Dinoverse, Janine doesn't take suddenly ending up in the body of a Quetzalcoatlus with total calm, but she adjusts much faster than the others, to the point where Mike asks her about it.

Live Action TV
"Connor: So...demons, vampires, doctors with claws... and I'm some sort of super-hero. *beat* Okay."
 * From Buffy the Vampire Slayer, the first time Oz is caught up in a fight with vampires, Willow hesitantly begins to explain the whole situation, prefacing it with "Now don't freak out..." Oz doesn't, because not only is he really that calm, but because the fact that vampires are real suddenly makes a lot of things about Sunnydale make sense. In the comics he tops himself by looking amused when his ex drops by outside the monastery he's meditating at, in a submarine, that she teleported to Tibet.
 * From Doctor Who, when Rory first walks into the TARDIS, both the audience and the Doctor expect him to look around in wonder, saying "It's Bigger on the Inside". He doesn't, and calmly explains that its another dimension before the Doctor can.
 * And really, the Doctor and anyone who travels with him is probably going to become at least a little Fantastically Indifferent. After all, when you're travelling through time and space with an 1100 year-old-alien who switches bodies, in a sentient Police Call Box that's bigger on the inside, while defeating monsters and aliens of all types, fantastic is an everyday occurrence.
 * Weird example in I Dream of Jeannie - while Nelson is used to magic (so he doesn't react with wonder to it per se), he does get caught flat-footed by what Jeannie does with said magic. Not because he thought it was impossible, but because of the situations it gets him in.
 * Happens in Angel, after Angel gives Connor the lowdown on demons and whatnot in "Origin":

Visual Novel

 * Masayuki in A Profile tends to react this way about almost everything. "Ah, Dissociative Identity Disorder? Neat. Can I meet your other personality some time?"

Web Comics

 * El Goonish Shive: Here.
 * Even more with Liz who is Highly Skilled at Not Giving a Crap.
 * From Questionable Content, Faye once mentions that it feels strange being so jaded that Pintsize's antics no longer surprise her.