It was a typical breakfast in the sewer lair.

Master Splinter had been awake for hours already and was deep into his morning meditation in his chamber.

Leonardo was silently collecting his thoughts over herbal tea, fruit, yoghurt and muesli, alert but contemplative, enjoying a more informal mode of reflection than his Sensei.

Donatello was quietly stirring sugar into his thick, black coffee, blearily rubbing at his eyes beneath the rim of his glasses and wishing he had got more than three hours of sleep.

Raphael was mutely shovelling mouthfuls of bacon, sausage and eggs into his mouth, washing it down with a protein shake and already anticipating a hard weights session that would help work out the morning grumps he always had.

Then Michelangelo woke up.

He barraged into the kitchen with a smile as wide as the Grand Canyon and a voice that echoed off the cement walls like the piercing ring of a cathedral bell. "Morning bros!"

As one, the others cringed and gritted their teeth. Leonardo shut his eyes with an air of the long-suffering. Donatello let his forehead fall with a clunk onto the tabletop and Raphael barely suppressed a growl.

As Michelangelo clattered from one end of the kitchen to the other, rattling pots and pans, opening (but not shutting) cupboards and drawers and generally causing chaos, he kept up a steady stream of chatter.

"Guys, you would not BELIEVE the dream I had last night! Remember that video? Of the cat that plays chopsticks WITH the chopsticks? Well, I totally dreamt the cat came to me and like, was my guide for a spiritual journey and we had to cross the double rainbow but like, half –way across the All Your Base Guy totally came down on us and we had to like, fight him and shit was getting really heavy and just when it looked like there was no way out, Charlie the Unicorn swept in and totally saved the day. Man. It was intense."

Leonardo's eyes met Raphael's across the breakfast table and the two brothers exchanged a look of black commiseration over their lot. Donatello sat up straight once more and nudged his glasses back into their proper place.

"I'm becoming slightly concerned about your propensity for dreaming entirely in internet memes, Mikey", he said mildly and Raphael shot him a caustic glance. That's all that was worrying Don about Mikey?

Michelangelo was oblivious, jumbling poptarts and toaster-waffles and chocolate milk onto the benchtop. "And hey guys – did you all see April yesterday?"

The resigned exasperation of the other three switched instantly into a tension so fraught the air could practically be cut. Donatello sat up straight as a pole. Leonardo's head shot up, his eyes wide and alert. Raphael's shoulders hunched over, his fists clenching on the tabletop.

Michelangelo remained oblivious. "Or rather – did you smell her? Oh my god!" Michelangelo carried his sugary breakfast over to the table and plonked easily into his usual seat, his expressive face animated with an ecstatic keenness. "Oh my god, bros, it was out of this world amazing! If you missed out – well, all I can say is I am so, so sorry for you," Michelangelo paused, a forkful of waffle smothered in whipped cream and caramel topping halfway to his mouth, his eyes shutting in rapturous memory as he tipped his head back. "It was awesome."

Raphael glanced edgily at his two sane brothers and noted they were both as stiff and tense as he was, Donatello staring ahead at some distant fixed point, his mouth contorted into an uneasy grimace whilst Leonardo was slowly, deeply breathing in and out, gaze focused on his tightly clasped hands.

Michelangelo shoved waffle into his mouth and chewed noisily, still not aware of the laden atmosphere in the room. "Man, I must've beat off over that five times last night."

Michelangelo's propensity to overshare about such personal matters was accustomed to by the brothers, if not appreciated or condoned. No one was under any illusions about what they each got up to – it was a household of four healthy young men, after all – but everyone seemed silently agreed that there was no need to discuss any of it amongst each other. Everyone except Mikey, that is.

It broke the spell. Leonardo snorted in disgust and reached out to smack Michelangelo upside the head. Donatello shuddered and flinched. And Raphael – Raphael glared at Michelangelo over the tabletop, wanting nothing more than to throw himself over it and beat some discretion – and respect – into his little brother.

"Don't talk about her like that," he growled, hunched so low over the tabletop his chin was practically in the remnants of his breakfast, glaring at Michelangelo with savage intent.

"What, bro?" Michelangelo seemed genuinely perplexed. "April is hot all the time, you know that, but yesterday – oh man, yesterday she was a thousand degrees Fahrenheit and there was only one way I was puttin' that fire out! And out. And out. Hey, s'not my fault it kept lighting back up!"

Raphael snarled and began to rise from his chair, his muscles bulging. Leonardo arrested him with a firm hand on his arm and in that moment it was all Raphael could do not to fling him across the room and wage all-out war on his brothers. But Leonardo wasn't letting Michelangelo off the hook.

"Mikey!" He snapped. "It is not appropriate or respectful to talk about April like that. Stop it."

Michelangelo glanced from one to the other of them, his mouth dangling open like a hooked fish, seeming genuinely to not understand.

"What's the big deal? I didn't creep on her. I wouldn't do that! But a turtle has needs! Believe me, bros, if you had caught a whiff you would've been doing the same."

And there was silence as the other three each went rigid, carefully looking at the walls, the floor, the ceiling, anywhere but at each other.

At long last, Michelangelo seemed to catch on to the mood in the room and his brow ridges leapt up his forehead, eyeballing each of his brothers in turn, a glint of triumph quickly sparking bright.

"Oh. Ohhhh hoooo. So you do know what I'm talking about, huh?" Michelangelo sat back in his chair and folded his arms smugly across his plastron. "Pretty special, wasn't it?" He smirked, enjoying his brothers' discomfort.

Raphael was too ashamed to do anything but stand stock still, bunching the muscles of his arms, fists clenching tightly. But through the cloud of his embarrassment he became aware that Donatello and Leonardo were both looking equally as mortified and just as much at a loss as what to do or say and he realised, with a growing feeling of horror and – there was no other term for it – territorial fury – that his brothers had all responded to April's peculiar intoxicating aroma exactly as he had.

And had dealt with it the same way.

Right then, the only thing stopping Raphael from clobbering them all was not being able to decide who to go for first.

Michelangelo yawned, scratched his plastron lazily with one hand and resumed eating, apparently content – for the moment – with the level of torture he'd just inflicted on his brothers. "Man, what was that about, anyway? I mean, how did she even do it? I felt like I was under a spell. A good spell, but still."

For the first time, Donatello quietly spoke up: "Menstrual cycle."

The others all looked at him, Michelangelo confused, Leonardo enquiring and Raphael furiously demanding. The sudden centre of attention, Donatello became nervous, hemming and inching his glasses up again.

"Well, uh, I did some research," he elaborated softly. "Human women have a hormonal cycle that operates monthly. For, um. For procreation purposes."

Michelangelo leant in towards Donatello, his face alive with fascination. Leonardo cleared his throat a little and tried to maintain a look of dignity. Raphael shifted his weight edgily, an uncomfortable and furious glower contorting his face.

"I'm sure we're all aware that humans don't lay eggs but they do produce them," Donatello continued in a mildly dispassionate voice, though the frantic tapping of his fingers against each other betrayed his nervousness. "Every month, an egg is released into the uterus and waits to be fertilised. Whilst this is happening, she will produce pheromones. To attract a mate." Donatello swallowed hard, his eyes darting anxiously all over the place. "Our sense of smell is stronger than theirs. I hypothesise it hit us all pretty hard."

That was one way of putting it, Raphael mused darkly, recalling all too well the overwhelming barrage of lust and desire that had consumed him the second that scent had hit his nostrils, how he'd wanted nothing more than to fall on his knees before her and beg her for the privilege of being permitted to even just kiss the tips of her fingers. He hadn't been entirely sure he would even be able to stop himself and the ensuing mortification didn't bear thinking about, so instead he'd just made himself quickly scarce. It hadn't stopped a frantic and frustrating jerk-off session in a tunnel not too far from the lair though.

Leonardo was pinching the bridge between his eyes with two fingers, trying to understand what Donatello was telling them. "Hang on, Donnie – you're saying this happens monthly?"

The implication hit Raphael in a horrible, hot rush and he swivelled his head to gaze wide-eyed and slack-jawed with dread at his geeky brother.

Donatello coughed and clasped his hands together, his thumbs twiddling. "Yes," he replied simply.

Leonardo gaped in disbelief whilst Raphael flung his hands up in the air and let them drop hopelessly by his side before he could help himself, swivelling away in frustration. Michelangelo still seemed confused.

"So – " he begun, his brow furrowing together. "What happens if the egg doesn't get fertilised? Do they just all stay in there? Wouldn't it get, I dunno, kinda crowded after a while?"

Donatello gave his immature younger brother an appraising once over, seemed to make some internal calculations and came to a decision. "Ah. You don't want to know."

For Michelangelo, it was sufficient. "Okay," he said chirpily and resumed the gleeful consumption of his nauseating breakfast, seeming neither to notice or care about his brothers' distress.

"Okay. Monthly," Leonardo seemed to be assessing the situation carefully, slowly rubbing his palms together and staring down at them with deep concentration. "The same time?" he queried Donatello, who shrugged.

"More or less."

"All right. Then it's simple. We just… avoid April at that time of the month."

Raphael whirled to face Leonardo with a vicious glare, unable to believe the sheer gall of his brother trying to tell him when and under what circumstances he could see April. As though he owned her.

"No way, bruh!" Michelangelo interjected around a mouthful of poptarts, pointing a thick finger at Leonardo for emphasis. "I'm not avoiding her any time but especially never at that time! That time is the best time to be around her! Anyway, why would she be giving off all those 'take care of me' smells if she didn't need to be taken care of? She was pretty upset, you know. Kept asking me if you guys were mad at her or something. I tell you right now, it took every drop of Mikey magic I had in me to make her smile. I made her an ice cream sundae and rubbed her feet and I even sat through that stupid The Sweetest Thing movie with her and you know what? It wasn't even that stupid! And I wouldn't have ever known that if I had tried to avoid her, like all you guys did, breaking her heart! And missing a really good movie too! I laughed a lot! Christina Applegate is hot!"

All throughout Michelangelo's impassioned speech Raphael felt his heart swell with fury and jealousy until it threatened to burst in his chest. He knew avoiding April like the plague whenever she was giving off that addictive scent was the only sensible course of action if he wanted to not make a complete and total idiot of himself, but he didn't want to any more than Michelangelo did. And hearing about how his infuriating little brother had got to spend so many hours with April all to himself, making her feel special when all he had done was make her feel repellent was causing him to grind his teeth in rage and resentment – at Michelangelo, but mostly at himself.

Donatello inclined his head with a quirk of his brow ridges, his arms folded over his plastron, corroborating Michelangelo's claims. "It's not uncommon for women to experience intense mood swings during that period of the cycle."

Leonardo shrugged, huffing in confusion. "So? That seems all the more reason to stay away from her around that time then."

Raphael shot Leonardo a glare that could've blistered paint, but didn't trust himself to speak without things getting really ugly. Donatello pursed his lips and glanced to the side, seeming unwilling to offer an opinion.

But Michelangelo thrust his lower lip out and folded his arms, shaking his head in deep disappointment at Leonardo. "That's just sexist, bro."

"What?" Leonardo sputtered in indignation, his eyes bulging. "I'm not the one who came in here and announced, uninvited, to the entire room that I - that – five times – "

"Shuttup," Raphael growled, deadly enough both Leonardo and Donatello shot him a cautious look. Michelangelo was already off on another tack, a dawn of understanding beginning to illuminate his face.

"Wow. I am suddenly starting to get a whole lot of jokes that went over my head before. It's like a whole new world is opening up. Oh man, that commercial makes so much more sense now!" And Michelangelo cracked up, gushing chocolate milk out through his nostrils so that Donatello and Leonardo groaned in disgust. Raphael could only slump back in his chair, gritting his teeth and gripping the edge of the table in a torturous confusion of emotion. Truth to tell, he wanted to beat all his brothers down for talking about April like this. It seemed invasive and tactless and he was pretty sure she'd be less than impressed to hear them.

But it wasn't just that. God, but he wished it were. It would be so much less shameful.

Knowing his brothers had all experienced the pull of attraction to her was making him feel possessive and territorial and he knew he had no right to feel that way. It wasn't as though he stood a chance with April, after all, but nonetheless this new information had led to a sense of urgency beating in his chest, an all-new competitive impulse as though he didn't already have enough – and he loathed it. It was hard enough dealing with his intense and helpless feelings for April at the best of times, but knowing that she would be even more desirable once a month, not just to him – but to his brothers, as well – it was too much for a turtle to take.

Raphael slumped over, his face in his hands as the remnants of his cold breakfast festered forgotten by his elbow.

"Monthly," he grumbled despondently into his rough palms.

Leonardo inhaled deeply through his nose and shot Donatello a searching glare, demanding confirmation. "Monthly?"

Donatello nodded once, abruptly. "Monthly." His voice was clipped, resigned.

Michelangelo grinned and pumped the air with both fists, his expression euphoric. "Monthly! This is gonna be awesome!"