School of Sanctuary
Tanner couldn't believe it. Two humans had infiltrated the Underground. None had done that before. Worst of all, he had let it happen. Now, two humans knew the greatest secret the Earth held, and he didn't stop them. Sadly, now he didn't really have an option to do anything except show them everything about it. They didn't have a way to erase minds, so that information would stick with them.
He paused to gather up the contents of his bag. They had fallen out at some point, so he put his sketchbook, pencil, and schoolbooks back in. Fortunately, they didn't see what he had been drawing. They might tell someone, and that wouldn't end well.
Fortunately, he had a plan. Sanctuary's head scientists had recently created something that would allow any monster to venture into the world above, with special permission, of course. These small switches, as they were called, triggered a temporary transformation that would disguise any one to have human characteristics. Very useful to the monsters like Tanner, who otherwise had no chance up there.
Tanner's father was head of these scientists. If he could possibly get his father to get him one of those, he could go up. In fact, the scientists were working on switches that could make monsters temporarily look like other monsters, like Centaurs to Nagas, or Merfolk to Harpies. Tanner could possibly snatch a couple of those and give them to Stacy and Jessie to use, so that they wouldn't be caught if they wanted to venture further into Sanctuary. Storage wasn't often occupied, so they were fortunate to not be caught.
In the midst of his brainstorming, Sanctuary's main thug approached. He was a harpy of the name Henrik, the same age as Tanner, except about ten times as strong. In nature, birds eat snakes. As a result, he had no interest in being anywhere near Henrik. Unfortunately, he didn't notice the harpy until he tapped Tanner on the shoulder, which woke him from his daydream.
"Hey, kid! Gimme that bag." And then proceeded to make a grab for his bag. He missed, but only barely. Tanner turned around, a few feet away, and stuck out his tongue. I childish gesture, yes, but an effective one. Naga saliva is very acidic, and can melt through stone. Henrik took a few steps back, called Tanner a name that he didn't wish to repeat, and flew off.
Undeterred, Tanner continued on his way to school. Detention was likely, for he was nearly two whole hours late. When he crossed the threshold into the school, he was met by the principal, a centaur named Mr. Horowitz. The students referred to him as "Mr. Horror-witz" behind his back. He handed Tanner a single slip of paper, paired with a single word: "Detention."
However, this didn't ruin his mood. He had a goal, and goals are made to be achieved. He remembered his schedule, at this point he'd likely missed his first three classes. With no choice but to face the music, he went into his next class.