Thermodynamic stability occurs when a system is in its lowest energy state, or chemical equilibrium with its environment. - [x]
The stray is in one of the laboratories, mixing things that oughtn’t to be mixed. The TARDIS likes this bit, although it does wrack one’s circuits when things start exploding. She’s had–will have? is having?–her walls singed this way more than once. But the repairs are simple and the fuss she puts on, mostly perfunctory. A bit of danger’s always fun, after all.
Crouching down to watch the flame, the stray bites her lip and slowly twists the knob of the Bunsen burner. Although she gives a wicked grin when she sees it flare, the TARDIS knows she is working with great care, in her own way. The stray leaps up again and reaches for a vial of something clear and volatile. With a steady hand, she tips it into the beaker and watches the mixture expectantly. After a moment, there is a startling pop and a single bright spark. The stray jumps back, then laughs as a thin plume of smoke rises from the beaker, the reaction complete.
The door to the lab swings open, cracking loudly against the wall. The stray jumps–oh, what do they call it?–again. (Words are funny.) The thief has been waiting in the corridor for the safest time to startle her, but the stray can’t know this, and she looks very cross.
“Professor! You scared me half to death. Why’d you sneak up on someone in a chemistry lab, anyway?”
The thief ignores her glare, smiling mildly and toying with his pocketwatch. “Ace, what have I told you about making Nitro-9 on the TARDIS?”
The stray sags just a bit. “Don’t?”
He seems slightly taken aback by this, and returns his watch to his pocket. “Well, yes. But if you are going to disregard the first bit, you could at least have the presence of mind to recall the second bit.”
“Which was?” She looks at him almost hopefully, one hand still hovering over the controls of the Bunsen burner.
“Safety goggles, Ace!” The thief rummages in one of the supply cupboards and produces two pairs of protective eyewear. Though the thief undoubtedly thinks them very advanced, the black reflective material reminds the TARDIS of nothing so much as the windows she has observed on certain Earth vehicles. The thief removes his hat in a single clever flip, and tugs one pair of goggles over his head.
The stray rolls her eyes at him, but underneath it she practically beams with happiness, and continues to do so even with the dark lenses shading half her face. She switches off the burner, removes the beaker, and reaches for another. The thief nudges it towards her, and they lapse into companionable science.
(There’s something funny about those words, too, but she’s not sure what it is.)
The TARDIS knows about the hole they are about to burn–are burning? have burned?–through the ceiling, and she has, accordingly, a truly impressive scolding prepared. But it’s all for show, and like the thief lingering outside the door, it can wait. For now, she is quite pleased just to watch.