A/N: Hey all! Miss me? =D So this is what happens when I try to write a one-shot. It goes TCRI on me and mutates additional chapters. But I'm sure no one's complaining, and even though Don and Mikey are set as the stars of this thing, it still has plenty of Raph and Leo. I actually didn't set out with the desire to make them the focal characters. It just happened, as lame as that sounds. They have a nasty habit of taking over any fic I try to write, the two goons. And as if that weren't enough, the Shredder and Foot somehow muscled their way into this, too, completely confusing the genre. I like to think I'm in control when I write, but obviously we all know better than that. ;)

The usual disclaimer still applies. Enjoy!

Deep below ground in the sewers of New York City, Donatello emerged from his bedroom with one of his many chemistry books tucked comfortably under one arm. Today he had spent the last hour reading about inflammable gases for no ulterior purpose than knowledge. It was something to learn, and learning passed the time on a dreary, downcast winter day like today. Not that any of them could see that it was downcast outside. The sewers simply had that familiar damp chill in the air that crept down to the bone and made the turtles inevitably sluggish.

As Don carried out the mug and plate that had not long ago accompanied him to his studies, his mind absently wandered back to methane gas. The cold in the sewers was growing worse by the day, yet in spite of his brothers' numerous suggestions, requests, and ideas, Don couldn't devise an efficient way to heat their home without soon losing the warmth to the countless drafty adjacent tunnels. It's not like the Lair was sufficiently insulated; sewers weren't exactly ideal domestic dwellings. And even then, securing a fuel source to produce the heat was a challenge in itself.

True, he had been able to tap into an electrical unit above and pirate power to satisfy their needs, but heating was an entirely different matter, all things considered.

Passing through the rec room on his way to the kitchen, Donatello thought wistfully of how the sewers were already teeming with methane gas—one of the main components of natural gas. He paused midstride, flipping open his textbook on a whim and thumbing through the pages until he found the desired chapter.

Methane is produced in considerable quantities from the decaying of organic solid waste. …In many cities, methane is piped into homes for domestic heating and cooking purposes. In this context it is usually known as natural gas, and is considered to have an energy content of 39 megajoules per cubic meter, or 1,000 BTU per standard cubic foot.

"That could be our solution," Don muttered to himself, lightly smacking the back of his hand against the page for emphasis. "If only I could somehow harness the natural methane we have right here, mix it with some key ingredients…" cutting himself off, he shook his head and closed his book with grim finality. Not only would such a cocktail of gases be nearly impossible to replicate, but methane was an extremely volatile substance. One lick of flame, and the whole Lair could be blown to high heaven.

The thought struck an unsettling cord.

Come to think of it, any fire in the sewers could easily set off an explosive chain reaction in seconds, devastating the surrounding network of tunnels. The disastrous implications hitting him like a blow to the gut, Donny felt a distinct shiver—notably unrelated to the weather—spread down his spine and vanish just as quickly as it had arrived.

How could he have overlooked such a blatantly obvious danger that posed a perpetual threat at home? After all these years, all it would have taken was the strike of a match and then boom, nothing. Their destruction wouldn't even be by the Shredder's hand, like the Foot leader so often boasted, but by their own. Unlike a ninja that could be crippled by a blow or avoided, this new enemy was ubiquitous.

He glanced in apprehension about his softly lit surroundings, finally keen to the danger that clung to the deceivingly empty space around him. What if…? He gathered himself with a steadying breath. No, all this time without incident couldn't just be mere coincidence. His family must know better. They had lived their entire lives in the sewers without any such disaster occurring, so they must have known the dangers fire would pose and acted accordingly. Taken preventative measures.

His shoulders sagging in unmistakable relief, Don managed a shaky smile in the face of this sharp scare and rounded the corner into the kitchen, crossing over to the sink.

As he rinsed out the dishes, he caught sight of Mikey from the corner of his eye and acknowledged his brother with a brief glance and a smile, turning back to his task.

"Hey, Mi-" Don immediately froze, mug still in hand, and did a rapid double-take.

"'Sup, bro?" Mikey called cheerfully as he heaved a pot full of water onto the stovetop and reached to turn on the burner. A gas burner.

Don's mind raced, his mouth suddenly dry. Since when did they have a gas stove? Since when did they have gas to work a gas stove? These questions were immediately shoved from his head, however, as his wide eyes locked on Mikey moving to turn on the burner that would produce a flame in a methane-riddled sewer.

Now Hamato Donatello wasn't usually given to cursing, but under such extraordinary circumstances, only one word came to mind.

"Shit!"