Cataclysm
Dumbledore was stunned, no, not stunned, it was worse than stunned; he was completely overwhelmed. The news of Harry's death hit him hard, it was more horrible than the news of Lily and James' deaths. Now theirs, he could understand, but in little innocent Harry's case, he had not expected it.
When he left the 15 month old babe on the doorstep of his only remaining relatives, he was sure that even though he would not be loved, he would still be cared for if only because of him being Lily's child. That alone should have appealed to the then bitter woman that Petunia was.
Dumbledore sighed, he was at a crossroad at what to do. Looking up and seeing that the Dursley boy still sitting before him, he made a decision on the spot. He would use legilimens on the child and search for memories of Harry's upbringing. In the case the ministry found that the wizarding world's savior was dead, he would be condemned to a life of resentment and shunned from society from his leaving Harry to the care of muggles, even if the muggles were Harry's relatives.
Bracing himself to keep the guilt at bay, he quickly sifted through Dudley's mind, sorting through the many memories the boy held. Flashes of Harry laughing, smiling and giggling happily met his eyes, and he breathed a sigh of relief. The child had been cared for, if the memories were to decide, it seemed that Harry was greatly loved and doted on by his aunt Petunia. Dumbledore smiled to himself, the memories of the Dursley boy could be used in his favor in court, if it would come down to that. Memories depicting a happy Harry being cared in a way that a mother would care for her son lovingly would definitely win over the female votes, and those who were compassionate at heart. Things were looking in his favor now.
He stopped.
Another memory had flashed before him. However, this one was not a happy one that showed itself, it was brutal and violent. This was the memory Dudley had of watching his father beating his mother in the kitchen; seeing his cousin Harry run to shield his mother, and finally struck down in an unconscious heap. Dumbledore was horrified at the scene presented before him; how could anyone abuse their own family to that extent. He sighed once again, feeling wearied and left the boy's mind and into the confines of his office.
He sat at his desk, rubbing tiredly at his temples and absorbing all the information he gained while in the boy's mind. This was not good, he decided. He looked straight up at the vulnerable child before him and made his third sudden decision of the day, to obliviate Dudley of the memory of his father abusing his mother and beating his cousin to near death. Taking out his wand, he pointed it straight at the oblivious child. Dumbledore's eyes dimmed as he looked saddened at his decision, saying a low, "I'm sorry."
He muttered a quick 'obliviate', stored his wand away and regained his grandfatherly façade waiting for the boy to regain hold of his surroundings.
Dudley shook his head and looked up at Dumbledore, a bit of confusion shown on his face. He looked apologetically at his headmaster, "I'm sorry sir, you were saying?"
"No, no, not at all child. I should be the one to apologize for keeping you here for so long," Dumbledore shook his head while smiling at the boy. "Well, off you go now. I'm sure your Head of House should be looking for you right about now."
"Oh, okay…sir," Dudley belatedly answered, stood up and left the room. Dumbledore's eyes returned back to its dim light and sadness rolled off him in waves as he watched the boy exit his office.
"No, not at all my dear boy," he whispered silently to himself, "I should be the one to apologize."