A seemingly invulnerable character reveals that they are actually deathly afraid of X... therefore, X is certainly going to be a recurring obstacle, no matter how unlikely. The Trope Namer is a line in Raiders of the Lost Ark, reminding us that Indiana Jones hates snakes when he discovers that the Well of Souls is crawling with them. A subset of Fatal Flaw. Fear of Thunder (also known as brontophobia) and Claustrophobia are specific variations of this. See Also Afraid of Needles (trypanophobia). Why do there always have to be examples?