The story of how Ishmael got his name is a favorite in his family, though he hates it. He’s heard it so many times it feels like he was there (he was there, kind of). Nobody can stop Dad from telling the story. Once he gets started, the unlucky listener has no choice but to sit through the tale once again. Dad might seem harmless to most, but once he gets going with the story, he’s like a “runaway semitrailer” that ends up in someone’s living room.
Here, Ishmael starts to introduce the idea that language is powerful. Describing Dad as a “runaway semitrailer” when he’s telling this story suggests that in these situations, everyone else is powerless—there’s no option but to listen to Dad’s story. Language, this shows, can be used to command attention and center one’s own version of events.
Ishmael’s second theory about Ishmael Leseur’s syndrome is that it can trigger “disturbing behavior” in other people. He used to think it only triggered odd behavior in Dad, but then he met Barry Bagsley and learned that his name can bring out the absolute worst in people. But now it’s time to hear the story of how Ishmael got his name.
Keep in mind that Ishmael, at 14, is probably far less interested in hearing stories from his parents in general—distancing oneself from one’s parents is part of growing up. So his referring to Dad’s storytelling as “disturbing” may just reflect where Ishmael is in his development.