So, today, we're writing about somebody you don't know.
In fact, we're going to directly address this person you've never met.
Don't know who they are or what they're like? No problem. That's the whole idea.
Invent details about your reader. Talk about their day, how it's going. Maybe what you noticed them doing in your newly omniscient state.
Talk about relevant details of their past. Create and detail thoughts going through their head.
You can shape it as a direct speech to them, or a letter to a person whose name you invent. It could be a radio broadcast meant for one person.
Bonus points if something epically unexpected takes place during the poem, or they come to some grand realization. They encounter a UFO. They realize the one mistake they'll never be able to repeat, though they wish they could. Air raid sirens go off. They find a letter from their mother or father revealing a dark secret.
Dig into this person. Dig deep.