I tried not to go OOC on this, so it is a bit shorter. Mainly because I found that Mycroft really doesn't argue that much, and I don't feel like he'd exactly break down, either. So... Here you go.
Mycroft had the unusual idiosyncrasy of tidying when he needed a break. He'd start with the lounge, then the kitchen, bedroom, and finally the two offices. Not that you minded, you dreaded the chore. That's just how he found it. The bloody book.
"Y/n, dearest, what is this?" He held the book in front of you, it was just a simple mother's guide, telling you how to cradle a baby, how to change diapers, and the like.
"A book on how to raise a child, I believe. This is interesting, why, exactly?" You of course didn't think this was a big deal, but Mycroft's composure seemed to dwindle, a fearful expression etched into his face.
"Because I found it in your office!" It was clear he was terrified of this, and with every right to be. Well, in his mind he had every right to be, at least. You groaned aloud, making sure your annoyance at his, what you considered, idiotic behavior.
"Yes, I suppose it would be in there, since it is my book." Mycroft's little amount of hope shriveled up and died, not only that, it showed on his features, as well. His eyes looked betrayed and fearful, while his lips went from a small, straight line of pink between slightly
parted to attempt to speak, back to the line.
"Problem, husband mine?" Mycroft and your marriage was by no means perfect, but arguments rarely broke out. Both you and Mycroft agreed and most topics, work always came first to the both of you, he had Sherlock to take care of and you had your sister, Pansy. Life was fairly smooth. Perhaps that's why this came as such a shock to the British Government.
"A-A child?" He asked in a sense of pure disbelief. You were as cold and cut off as he was, if not, more so. Why on god's green earth would you of all people want to have a child.
"Yes. A child, Mycroft. You know, an infant?" You tried explaining it in a simpler way, but by the look on his face, he was still far from understanding. A thought occurred to him, which seemed to settle him a bit.
"Are you-?" He didn't even want to finish the question. It was naïve, hopeful thinking anyways.
"No, of course not." You rolled your eyes in a bored fashion. His nerves picked up again, but instead of fear their was more upsetedness this time.
"Why would you want a bloody slobbering, pooping, and annoying brat running around?!" You looked boredly down at your nails.
"Because. We are two of the smartest, if not, the two smartest, people this planet has seen. A child with the mathematic capabilities of my mind and resourcefulness of yours would be unstoppable. Besides, children are one of those symbols of a 'loving' marriage, yes?" Mycroft usually loved the side of you that could win any argument. You didn't take seven years of debate for nothing, after all. Right now though, he wanted it to shut up, and stay shut up.
"It's a form of sentiment, and sentiment is a weakness only found on the losing side, you must know that!" The only retaliation he had. You smirked, already knowing you'd win.
"Fine. Then I'll have the divorce papers signed by, say, does tomorrow sound good?" Checkmate. A woman as cold as him with the mind of both a career politician and a maths professor was definitely a dangerous mix. A dangerous mix, indeed.
"What ever do you mean, wife mine." He said through gritted teeth.
"I mean our marriage is a form of sentiment, so if you wish not to have sentiment, then you wish not to be married." You picked up your wine glass, taking a slow, small drink. Mycroft searched for a comeback, anything to talk you out of this.
"Two options, dearest. One, have a child and accept sentiment, or two, don't accept sentiment and get a divorce. Tick. Tock." Here it came...
"Fine. We'll have a bloody kid." He slumped into his chair, not bothering to look your way.
"Good. Glad we've reached an understanding."