Percy was always one of those fellows that thought, "When I finally get out of this place, I'll leave and never look back." He didn't realise how much he'd miss home until he was forced to stay away for so long, even if only by his own pride.
Siding with the Minister, Percy realized after a short amount of time, may not have been the wisest idea. Really, he had mostly done it to prove that he was not as much a failure as he considered his father to be and that he was going to become the youngest Minister of Magic in history. He knew that this meant betraying his family, but, at the time, he didn't care. Too wrapped up in his own sense of self-righteousness, he cast his family aside like an old sock. It wasn't until later that he realized what he had given up.
Whenever he would see his father in the Ministry, Percy would feel a twinge of guilt that he would quickly snuff. As time went on, though, the twinges became harder to ignore. From the gnawing feeling he began to feel in his stomach, Percy derived that he truly missed his family. But being the prideful young man that he was, he felt it was only right for him to stick to his decision regardless of his feelings or his family.
Slamming the door in his mother's face on Easter was a real turning point. After the door banged to a close, Percy put his back to the door, and slid to the floor as his listened to his mother let out a small sob and leave. He put his head in his hands and wept bitterly. How had he let his pride go this far? If he couldn't accept this outreach of kindness, what would it take for him to forget his pride and return to his family, confessing from the bottom of his heart how much he missed and loved them?
When the war for Hogwarts and the freedom the Wizarding world began, Percy decided that his time had come. If his family was going to fight or even die for freedom, than he would fight and die beside them. But his pride had carried him too far away from his family. Percy spent only precious minutes with his brother before he fell. Because of his pride, he hadn't even had time to tell Fred how much he loved him and how much he secretly enjoyed the pranks he and George used to pull on him…or how he would never forgive himself for letting his pride separate him from his family.
Percy returned to his family home after the war. But some wounds never heal properly. Percy never let go of the loss of his brother. Blaming himself, he became a shell of his former self, meek and quiet, going to work in the morning, and returning home at night. No longer fostering dreams of glory, Percy quietly absorbed as much time with his parents and siblings as he could, no longer absorbed in his pride. No longer possessing any.