"...If metal can conduct heat, it can conduct electricity..." This was said in response to Astrid's findings as he watched the countdown, clearly a preoccupied and outspoken linking between these things. "Lightning is a form of electricity. Electricity is contained, controlled. Electricity can also produce fire– heat. Metal's just there to help it along..."

Before he could go any further with that, there's a telltale trill. The microwave shut itself off right then, making Hiccup jump to open the door and take out the plate.

He did this rather quickly, placing it clumsily on the counter. "Ow! Hot!"