Neighbors might also be characters. Some could be helpful, calling for help or trying to assist in some way, while others might just be onlookers.
There could be the homeowners, who are in a state of panic as they see their home burning.
Accidents in the kitchen are quite frequent. As I mentioned before, leaving cooking unattended can lead to a fire. Also, a grease fire can start easily if the oil gets too hot while frying something.
The 'house on fire short story' might be about the chaos and danger that a house on fire brings. It could focus on the people inside trying to escape, their fear and panic. Maybe it also shows the efforts of the firefighters to put out the fire.
You could start by describing a character with a motive or a reason for wanting to do it. Maybe they're seeking revenge or have a mental breakdown.
One common cause could be an electrical fault. Consequences might include property damage and even loss of life.
Isolation could be a theme. The house might be a place of isolation, and the 'head' could be the only or main element within that isolation, perhaps representing a lonely figure or a solitary thought.
Maybe it's about a drought-stricken land where water is desperately needed, and a fire threatens to make the situation worse. Or it could be a tale of two characters representing fire and water and their complex relationship.
Perhaps it was following a signal. There could be something in your house that emits a frequency or signal that the alien detected. It could be a simple electronic device or even something natural that gives off an energy that the alien mistook for something important. Or it might be that the alien is a bit of a mischief - maker, and it just randomly chose your house to have some fun and see how humans react.
Not necessarily. It could be a blend of truth and imagination. Maybe there's a kernel of a real story, but it's been embellished and fictionalized to make it more engaging.
Definitely there would be the maid herself. There might also be the employer, who could be a wealthy person with high expectations. And perhaps there are other servants in the household who could be friends or rivals of the maid.
Since the main character is Waldo, there could be his friends, family members or neighbors. For example, a best friend who goes on adventures with him.