Tutoring and Tierra

"Are you taking extra Defense Against the Dark Arts lessons?" After Saturday breakfast, Zacharias Smith cornered Harry in the Entrance Hall. He had originally wanted to ask Harry about the Gryffindor House Quidditch team's training schedule, but had unexpectedly heard this news. "Oh, Merlin, Harry, haven't you already chosen Tierra's Dark Arts class? Why do you need to study Defense Against the Dark Arts too?"

"Well, because... because my Godfather came to visit me a few days ago. You know..." Harry racked his brains for an excuse.

"Ah, I know," Zacharias Smith blurted out. "Your Godfather nearly got into a fight with Snape."

"If Tierra hadn't stopped them, they probably really would have fought," Zacharias Smith said tactlessly. "What a shame they didn't."

Harry: ...

"But what does that have to do with you getting tutoring from Snape?" Zacharias Smith pressed relentlessly.

"Because my Godfather won't let me take Tierra's Dark Arts class. Sirius, he... he seems to have some prejudice against Tierra. He still thinks Dark Magic will definitely taint our souls," Harry said, half-truthfully and half-made-up. "That day, he... he came to discuss it with Headmaster Dumbledore. Of course, although Headmaster Dumbledore couldn't persuade him completely, he did make him compromise. He'll only allow me to attend the theory portion of Dark Arts, not the Practical Class. If I can't advance into the Dark Arts Practical Class, I'll be short on the practical credits I need to become an Auror, so... I have to make up those practical credits through Snape's Defense Against the Dark Arts class. And since the term is already half over, Snape refused to let me join his current class on the grounds of course-selection regulations. So, after Tierra and Headmaster Dumbledore took turns persuading him... he agreed to open a small class just