Elementary has dealt with resurrected extinct mammals, fake dinosaur fossils, and tiny deadly mosquito drones. So parallel Watsons and a bizarre time machine wouldn't be too far out of Joan's wheelhouse.

The nicknames were a shortcut that kept me from having to write "the Holmes with the curly hair and long coat" vs "the Holmes with the dressing gown and aquiline nose" and "the sickly young Watson with the bad limp" or "the Watson with the thinning grey hair."

Joan Watson does way too much, I agree. Doing lightning-fast MLP fanfic is just the icing on the cake.