Fred was naturally observant - it came from years of watching around for Filch or McGonagall or their mum. Even so, he almost missed seeing his brother walk past because there were some very pretty girls out today - all feeling the need for ice cream at the small shop next to the pasty shop, apparently. He grinned at one, wagging his eyebrows, but something distracted him....
...something familiar about the head of red hair buried so that all you could see was the top of it as the man walked, and about how tall and thin and straight and pompous he was even when he was just walking into a shop. How could you be pompous when you had your hands buried and you walked like you didn't want anyone to see you? Fred didn't know, but Percy managed it - always had.
He considered following him in, but the shop was crowded. Whoever came in, had to come out.