Acid

John stepped into the shower tiredly grumbling about the lack of sleep and was surprised when he stepped on a glass beaker which toppled over leaving the contents spreading in the bathtub around his feet. It took him only a second to realize that something was wrong and when the burning sensation started to spread under his foot he was swift to start the water running, hoping for dear life that whatever had been in the beaker wouldn't react badly with water because he really did need to clean his foot because it felt like it was being set of fire.

Ten minutes later he limped out of the bathroom in search of bandages and Sherlock to yell at, not necessarily in that order.

Sherlock is nowhere to be found and when he does return two hours later it is to find John leaning against the kitchen counter trying to make tea while keeping weight off his wounded foot.

'Good you're back, you can make tea then, I need to sit down.' John stated with a bit more steel in his voice than he had initially intended.

'John, I thought we sorted this, your limp isn't real, stop being so dull and make your own tea.' Sherlock quipped with a distinct lack of compassion.

'It is bloody well real now, since you left acid in the bathtub.' John cried hobbling toward the sofa, leaning heavily on his old cane.

'Oh, what did you do with it?' Sherlock asks with a slight frown.

'Well, I bloody well, stepped in it didn't I, and yes, then I rinsed it down the drain because really I was more concerned with the burning pain in my foot than preserving whatever experiment my crazy flatmate had left in the bathtub.' John all but shouted.

'You could have just removed the beaker from the bathtub, that would have prevented this rather efficiently.' Sherlock states simply and John doesn't bother to answer, why argue with a selfproclaimed sociopath. It wasn't worth it.