I left the family because I was young and scared. I'm just barely old enough to remember what had happened the time before, to remember uncles Fabian and Gideon going away and never coming back. But more than that, and perhaps even because of that, I had faith in The System. The System locked up Antonin Dolohov, the bad man who killed my uncles. The System was simple and without feelings and it made sense, even when the rest of the world did not.
What's more, I could be someone in The System. At home, I wasn't the cleverest or the kindest or the funniest. My quiet nature and patient respect for the rules earned me more ridicule than respect at home, but when I put on my Prefect badge or got behind my desk at the Ministry, that behavior made me someone successful. So that's why, when I was made to decide between my messy, loud, loving family and the cold, precise comfort of The System, I chose what I did. What else would I have done? I trusted the Ministry beyond anything, even my family. Especially my family. Like the others, I spent my school years embarrassed by our poverty. Once I realized that I was destined for the Ministry, I was even further embarrassed by our family's reputation and Father's low standing. I'm not proud of it, but I wanted to distance myself from all that, and by the time Voldemort had returned, I'd distanced myself so much as to not be able to go back. I couldn't turn back to the family after I'd spent so much time and effort getting away from them and running towards the precious System.
Then, when it was confirmed that Voldemort actually -had- returned, it was too late. Proud Percy could not turn around and admit that he had been mistaken. Especially because I'd risen to even more power within the Ministry by further denying my family. It was not yet time to return to them.
Then Hogwarts was under attack. Hogwarts, the place where I'd first tasted Order and Power and The System. Not only was Hogwarts under attack; it was under attack from members of the Ministry. For ages I'd known, deep in the back of my mind, that parts of the Ministry had been working for Voldemort. But when the Minister himself left with the Death Eaters, I knew I had to swallow my pride and go back.
So I went. I briefly rejoined the family and tried to apologize for what I'd done, but I knew that in that moment there weren't enough words, and that I'd do better with actions.
It was like an enormous weight had been lifted off of my shoulders, admitting that I was wrong, and I could run through the embattled halls of the castle and defend my school and my family and a cause. I was so happy, I was actually laughing and cracking jokes. Me, Percy, who "wouldn't recognize a joke if it danced in front of him wearing only Dobby's tea cozy," was smiling and teasing the Minister of Magic as I fired curses at him.
And then it happened.
Fred.
Fred, who had laughed his whole life, laughed one last time at something that I, Percy, had said.
In that moment, while I was sick with shock and grief, I was happy. Happy that I had come back to my family, happy that we would mourn together. Feeling all of those emotions together, emotions that I had been hiding from within my beautiful System, assured me that I had done the right thing.