Storm Drains: Fantasy

The clatter of their shoes echoed against the empty tunnels that would flood with water when the storms came. It was the peak of summer though with not a storm on the horizon, so they'd taken the liberty of slipping down through drains whose grates had rusted off, by climbing up culverts until they were inside the drain storm-system proper. Their marks still glowed on the walls from the last time that they had been able to gain access--a quick slash of phosphorescent paint and their territory was marked, lest any others had thought to set up residence in the tunnels. "Do you think it worked?" asked Toby, a big guy but not one who could think ahead very far. "Do you think we caught a mermaid?"

Inspiration: ?
Story Potential: Low. Oh, God, so low.
Notes: It's amazing how quickly a character can become hackneyed.