Percy really liked his freckles. He only had a few, and they were all on his arms, so most people didn't even know that he had them. But Percy liked them. They reminded him that he was a Weasley. He was built like Bill and Ron, but they were both covered in freckles, just like Charlie and the twins. And since he was the only one in the family who needed glasses, his appearance had always been far removed from that of his brothers. In short, he looked like a random redheaded person, not a Weasley.
And that was why Percy loved his freckles. They were proof, in his mind, that he really was a Weasley. As mad as he was with his parents sometimes, he still couldn't imagine not being a Weasley.
But now, his freckles were ruined. Covered. Marred. Gone.
Replaced by an ugly black brand that erased his old identity and declared that he was now a part of a new family.
He was no longer a Weasley.