You're suddenly about three pounds heavier, which really isn't that much when you think about it, but you don't like to think about things like that. You only justify things that you want to do – if it's a negative you dwell on it or ignore it, and this isn't something that can be ignored. Weight has a gravitas to it. (Which is a dumb phrase that says nothing and just sounds intelligent. It's like saying something has a certain je nes sais quoi. It literally doesn't mean anything. Any understanding is purely semantic.) And little voices you're definitely ignoring are saying that three pounds are better than the fifty you woke up with, or the spare few ounces you could have had for a few days, but these voices are annoying and being ignored and are being reasonable and you don't think it's that much of a stretch to say you don't really have to be reasonable about suddenly being full of metal. Particularly when you weren't that reasonable to begin with. For somebody so inclined towards all things mechanical and mathematics, you're surprisingly erratic, and it probably drives people crazy.
Good. It's better that way. People are more interesting when they're on edge. Or inversely when they're completely relaxed. It's all that shit in between that's irritating.
Three pounds doesn't seem like a lot, but in terms of the human body, it's pretty fucking goddamn important. The average human brain – which yours isn't. Average. Some might say human, but then again, you've done a pretty good job proving exactly how human you are, time and time again – is usually three pounds. Three very important pounds. The heart is just shy of a pound when you're young but gets bigger with age, so by the time you pass on, with an average of three broken hearts, you work out that the heart's about three pounds as well. (This is worked out on a night you don't really remember that well: just the conclusion you came to.) A healthy human liver is about three pounds, and yours is also very important. One of the most hardworking organs in your body, aside from your brain. Three pounds in the human body is a big step. Three new pounds in a place they weren't before? That's an entirely new kind of step. The kind of new kind of step that's there when you don't expect it to be and makes you stumble a little and look like an idiot because hey, dumbass, there was nothing there except the floor.
Three new pounds in your chest. Your chest is in a different shape now. Sort of. The arc reactor is sitting where a part of your sternum used to be – actually where about half your sternum used to be, and as a result, most of the muscles in your chest don't connect the same way they did before. You've grown accustomed to it now, although every now and then when you're not paying attention you forget that you have to breathe differently now than you did for the first thirty-odd years of your life and it all catches up with you in a rush of chemicals you wish you were less familiar with.