From Al's point of view, at least, it all started something like this:
Military junior dormitories, 4:43 PM
"Al!" Edward banged open the door to their dorm hard enough to add a new dent to the collection on the wall. "Get all your stuff, we're leaving, right now, hurryupdon'twait!"
"Eehhh?" Al jerked upright on the chair, causing it to squeak mournfully. "Leaving? Now? But brother, why?"
"No time to explain, just pack!" The words were for more for show than for action, seeing as Edward was the only one with the need to pack. He was already humming around the small room, tossing things into his suitcase. "The express train leaves for Souswell from Bridge Street Station in seven minutes, we'll just have time to make it if we run!"
"Bridge Street? But I thought we were leaving from Central, and not for another two hours," Bewildered, Al nonetheless put a marker in his place and tucked the book away inside his armor for safekeeping.
Edward shoved the clothes down into the case and closed it with a practiced snap. "That takes too long," he said, "and besides, he could call ahead and stop the trains. Anything you care about it, take with you, or it might not be here when we get back!"
"Brother, wait!" Al quickly grabbed a few more of his books, as well as a towel to wrap them in. "Why are we in such a hurry?"
"Explain on the train, no time now," Edward said, hefting his case over his shoulder. "He's still at HQ, but he'll be coming out any minute now, and once he does, we're going to be far away from Central!"
"He who?" Alphonse complained, trailing after his brother as they vacated the dorm room. "Brother, you didn't explain anything! What's going on?"
Now, no doubt you in the audience, like Alphonse, would like some explanation as to what's going on. Perhaps it would help if we went back in time, somewhat, to the prior events of the day...
Officer's lounge, Central HQ, 4:35 PM
"I am going to kill him," Roy Mustang said, slowly and distinctly.
"Surely you don't mean that, sir," Lieutenant Hawkeye murmured. But she kept her tone subdued, so as not to draw too much of her commanding officer's wrath down on her head instead of poor Havoc's. It took a great deal of iron will to keep her face completely deadpan, but she managed it.
"Oh yes, I mean it all right," Roy said ominously. "First I am going to track the little brat down, and then I am going to disable that bloody arm so that he can't so much as snap his fingers to do alchemy, and then I'm going to —"
Perhaps a little further back.
Grand lobby, Central HQ, 4:28 PM
"The first one of you to say so much as a word," Roy Mustang said as he stalked, seething, through the hallway, his subordinates following at a cautious distance. "The first word I hear from any of you that is not 'Yes, sir' or some variant on that theme, and that unfortunate person will find themselves scrubbing toilets for a month, am I understood?"
"Yes, Sir," said Breda.
"Yes Sir," said Fury.
"Yes Ma'am," said Havoc.
Err, not quite far enough.
Brigadier General Roy Mustang's office, Central HQ, 2:20 PM
Life was good, thought Roy.
The sun was shining, the birds singing, and he had a whole new list of phone numbers tucked away inside his desk. He was one step further up the ladder to becoming Fuhrer, with this brand-new promotion. And even better, he thought, with the ceremony this afternoon to prepare for, Hawkeye couldn't make him sign off on any paperwork.
Yes, the world was looking bright, Roy thought, and it was making Edward's palpable fury and frustration all the more enjoyable. He smiled slowly across the desk at the boy, clasping his hands across the blotter.
"Are you sure you have time to be here, Fullmetal?" he purred. "After all, your train leaves for the North later tonight. It is going to be," and he paused for emphasis, savoring every moment of it, "a long, cold journey, so don't you think you ought to prepare?"
He saw the muscle in Edward's jaw clench, as though the boy were biting back some very unpleasant comments. Watching him swallow his frustration was almost as satisfying as watch him fly into a rage, though, so he didn't bother to needle Ed any further.
Ed bared his teeth in a caricature of a smile. "Well, there's not that much to pack," he said, "and since my afternoons are open all the time now, since you gave our research project to someone else—"
"Are you still upset about that, Fullmetal?" Roy said with some surprise. "You shouldn't be so possessive of your pet projects, you know. That research does more to aid humanity in the hands of the Academics department than at the whims of the hands of one, small boy—"
"It was Al's project too," Ed said through gritted teeth, and shot him a burning glare, "and it doesn't hurt that having 'discovered' the project, all of the credit goes to you now, doesn't it?"
Roy couldn't help it; he smirked at the reminder of his little piece of finagling. "Can I help it if, due to my position, I have greater visibility?" he said innocently. "Your name is still on the project, Edward. It's simply more likely to be—"
"Don't you dare finish that sentence!" Ed said, outraged.
"—overlooked," Roy finished anyway. He raised one eyebrow, challenging Edward to object.
Ed opened his mouth, and then closed it. "Visibility is that important to you, huh?" he said.
"Of course." Roy rose from behind his desk and paused to straighten out an imaginary crease in the front panel of his dress uniform. "There are hundreds of colonels in the Western Army, Fullmetal, and dozens of Brigadier Generals. Now, you and I may know that I am far superior to all of them—"
Ed made a noise that could charitably be called a snort of disbelief. Roy chose to ignore it.
"—but that does not matter if I cannot be seen. And now, as much of a pleasure as it is talking with you, Fullmetal, it is time for me to go and do just that."
Ed was staring at him, Roy noticed, as he picked up his cap from the desk. He couldn't quite fathom his expression.
"Mustang," Ed said abruptly, "is it all right if I go in with you?"
Roy lifted both eyebrows, this time, in surprise. "I find it hard to believe that you'd want to," he said. "The ceremony will likely run on for quite some time before I am even called up to give my acceptance and thanks."
"That's all right," Ed actually sounded interested, if that was possible. Was it possible for Ed to be interested in things other than his brother and alchemy? If so, maybe Roy ought not to discourage him. It certainly wouldn't hurt either of them for Ed to have a better understanding of the internal workings of the military.
"Certainly, then," Roy replied. "It's customary for the newly promoted Brigadier General to have his staff with him at the acceptance ceremony; it shouldn't be too difficult to fit you in."
Wonder of all wonders, Ed actually saluted. "Thank you, Colonel!" he said, and the eagerness in his voice was there for anyone to hear. Roy actually felt a pang of guilt for badgering the boy so incessantly lately.
Perhaps he should let up on Ed-baiting as a pastime, and rely on it only when necessary. Well, the missions couldn't be helped, and the project really WAS better for everyone in the hands of specialists. But perhaps, now that he had reached his promotion, he could emphasize Ed's leading role in the project a little more.
At the very least, he could stop teasing him about his height so much. Roy smiled at Edward, with more warmth than his usual smirking grin, as the two of them went out of the office together.
Now, probably none of you in the audience are terribly interested in listening to an afternoon full of speeches. So perhaps it would be helpful, once again, if we skipped forward a little bit.
Main Assembly Room, Central HQ, 4:15 PM
There was a dead silence in the hall, as the echoing bang of the door and the oddly lopsided footsteps pattered away in the distance. Nobody seemed to be making any effort to stop him, and Roy gritted his teeth as the blood beat in his ears, wishing very fervently that he didn't have to be stuck here, so that he could go after Ed personally.
He cleared his throat, and again, feeling the eyes of the entire assembly on him. "Gentlemen," he said, and was almost pleased with the smooth way that came out. "I, ah, can explain this...."
Whoops, a little too far.
Main Assembly Room, Central HQ, 4:05 PM
The last of the three-star generals finally ran down with their canned speeches, and Roy felt more than heard Ed shifting in his place next to him, checking his watch. The Fuhrer was just sitting forward at the podium, introducing Mustang and announcing his promotion—as though anyone there didn't already know, he thought. He kept his expression attentive and grave on the outside, though on the inside, a part of him was basking in the recognition.
"Mustang," Edward hissed, low enough not to be audible over the chamber's echoing acoustics. "I can't stay any longer or I'll miss my train. Gotta go."
"Mmm, very well," Roy said out of the side of his mouth. He gave no sign either to the watchers or to Fullmetal the sudden disappointment that Edward wouldn't be watching for his speech. Then the assembly was rustling and clearing their throats, shuffling papers if they had them, and it was time for Mustang to go up to the podium and formally accept.
As he stood, he turned slightly towards Edward and added in an undertone, "I'm sure if you duck a little, they won't even be able to see you over the desks."
That was his last mistake.
Roy had only gotten one step towards the spotlight when there was a sudden sharp noise behind him, an echoing clap, and he stumbled forward as small, hard hands landed in the middle of his back. He froze, and that was probably a mistake, but it was what he'd been trained to do, what any alchemist was trained almost from the first day: when another alchemist's reaction goes off, don't move, don't speak, don't do anything to disturb it, because the results are wildly unpredictable.
So he froze, while in the middle of the General assembly, in front of the entire High Command of the Western Army, and in front of the Fuhrer himself, his best dress uniform was suddenly converted to a sweeping blue woman's evening gown.