At the train station, Harry was introduced to the Grangers. Everything was very cordial. When they arrived at the house, he was shocked to learn that Hermione's sister didn't seem to like either him, or Hermione, at all. Being who he is, he confronted the situation.
"Excuse me, but do you have a problem?"
"What? No, I don't have a problem. I have faith."
Harry just looked confused at that, so Mr. Granger explained, "Before Hermione got her letter, we were a Catholic family. However, we refuse to follow a religion that condemns our daughter to Hell. Especially since it isn't her fault that she is what she is. Jessica, however, continues to believe." Harry didn't believe in a god. At least not a just one. However, he could tell that this was a sensitive issue in this household, so he'd drop it. Hermione changed the subject.
"Harry, are you not going to wear your suppressor?"
"No, I doubt I'll be in danger of accidental magic this summer." The Grangers, confused, asked what a suppressor was. "I am very powerful. Very very. So powerful, in fact, that I'm nearly omnipotent. So sometimes I suppress my power so's not to have accidents." Using the term 'Omnipotent' was probably a bad idea.
"That's it. I can tolerate Hermione's constant studying of her devilry, but this is ridiculous!" 'Well, that didn't last long.' "God is the only all powerful being in the universe!"
Harry looked down, thoughtful. Jessica thought that he was feeling sorry. After a moment, he said, as though coming upon a realization, "You are right." Jessica was now hopeful that she had saved this poor heathen. "I...must be...God!" Just as soon as he said his last word, he created a beam of light around himself, and looked up into the heavens.
Jessica exploded (not literally), "Oh My God! You are so stupid!"
Harry looked scandalized. "Why you blasphemic -"
"You aren't God!"
Here, Hermione jumped in, though she was having a hard time keeping a straight face. "You heretic!"
Jessica started stomping up to Harry, but her parents were holding her back. Harry started acting as though Hermione was holding him back as well.
Jessica screamed, "I swear if you defile God's name one more -"
"What?! You want to try the Omega? I'll go Old Testament on your ass!"
"Try it! I'll burn you at the stake, you satanic little prick!"
"That's it! You are so freaking smote. You better get ready for an eternity in purgatory. Nothing but daytime TV and pinball!" It was at this point that Harry and Hermione cracked up. Neither could hold in their laughter. The adults were clearly hiding smiles, but trying not to take sides. Jessica just stomped up stairs and locked herself in her room.
Harry ended up having to send a letter to the Ministry of Magic explaining that he was the one that did magic at the Grangers, rather than Hermione. They did the sensible thing by appologising to Hermione and then ignoring all magic coming from that residence for the remainer of the summer.