Just had a random day dream about Percy (again.)
What if after the war had ended and Fred survived, Percy didn't reunite with his family and took a break from his job to go to the muggle army?
Like during the war, Percy had forged papers for muggleborns and halfbloods. Helping them evacuate in secret under the nose of the corrupt ministry.
But a few of them don't make it and Percy feels guilty because he thinks he didn't try hard enough.
So he joins the British muggle army, at 20. He stays in service for around 6-7 years. Because he wants to help in some way. Obviously he doesn't take his wand, he's intelligent, we already know that.
His family won't even know about it until they see the news on the muggle tv that Arthur finally got to work. They see a video on the news channel where the soliders are setting up their tents after marching and they see Percy among the crowd of soliders.
I think it would be an intetesting concept and I would love to see someone have a long fanfic on it.