Piers Polkiss knew that he was Dudley's staunchest friend. Oh, he wasn't foolish enough to believe that Dudley realized that, but all the same, he himself believed that it was true. He'd put up with a lot from Dudley over the years, and he couldn't even explain why.
The simplest explanation was that Piers had never lived one moment of his life outside of Dudley's shadow. There were very few baby pictures of Piers alone; most were of the two of them together—Piers and Dudley crowded into one playpen with all of Dudley's toys surrounding him, Piers watching as Dudley played on his new rocking horse, Dudley looking on begrudgingly as Piers took a solitary lap on his new tricycle (with Mrs. Dursley standing behind him beaming at how her son was learning to share). As they got older, Piers started to have actual memories of their times together. By that time, their friendship wasunquestioned by everyone, including himself. Eventually they'd started school together, and then they'd even gone off to Smeltings together. Piers had literally never been separated from Dudley for more than a week.
Through all this, no matter how badly Dudley might have been treating his "best mate" at any particular moment, there was always someone who fared much worse—Harry. Over the years, Piers had found it best to ignore Dudley's cousin entirely, but sometimes that was impossible. On those occasions, Piers had realized how lucky he really had it. Dudley talked to him civilly most of the time, occasionally shared his belongings with him, and even once in a while said something nice to him—courtesies that he never extended to Harry. Over time, that had come to seem like enough, and he'd consoled himself with the realization that there was nobody in the world that Dudley treated any better.
But now that carefully constructed mythology was tumbling down around him. Dudley hadn't been able to talk about anything but this Draco kid for the last couple of weeks, and now he was showing him kindnesses that Piers had never experienced in almost 17 years of friendship. Piers was feeling rather disconsolate, and he didn't buy that "my best friend who lives in Little Whinging" line for a moment.
Even so, nothing had prepared him for what was about to happen next. The lookout ran into the playground, yelling "Mark Evans is coming!" and the gang immediately sprang into action. A couple of the guys took off running after the small 12-year-old, and before long they'd dragged him back in front of Dudley, who was sitting on the one working swing much like a king holding court on his throne. Piers moved to assume his traditional role. Other gang members could catch someone, but Piers was the only one Dudley trusted to hold them down while he punched them. However, this time as Piers got up off the grass, Dudley motioned for him to sit back down. "Draco," he said, "I'm going to give you the honor of holding this dirtbag down while I give him what he's got coming to him."
Piers' entire world fell apart, only to come back together again in the next instant, when Draco exclaimed disdainfully, "You want me to do what?"
"Just hold him down while I punch him," Dudley repeated. "Haven't you ever done that before?"
"No, and I certainly don't intend to start now," Draco said adamantly. "Malfoys don't dirty themselves with physical violence."
For an instant Dudley looked like he was about to cry, but he quickly restrained himself. "All right then, Piers," he said. "You know what to do."
Piers rejoiced inside as he moved to take his usual position. From his vantage point, it was the best beating that Dudley had ever given.