Gulliver Oin

Gulliver Oin—just "Mr. Oin" to his students—is Niamh's social studies teacher at Teras High School. As a teacher, he's competent but uninspiring, but while cynical and usually seeming bored out of his mind, he's among the teachers most proactive in involving themselves in their students' lives... for better or for worse.

It's Mr. Oin's top head that does all his talking, probably because his side head's arthropodous mouthparts prevent it from speaking intelligibly. Nonetheless, apparently the two heads have separate minds and some mental connection exists between the two, because the speaking head often thanks the other head for reminding it of something or coming up with an idea.