Red Thread hit us by the broad range of meanings, across very different cultures.
In the Ancient Greece, for example, Theseus was guided through the Minotaur labyrinth following a red thread Ariadne gave him: he tied one end to the entrance gate and found his way around by trial and error, thanks to the thread guidance.
Going further East red threads are related to destiny: a legend claims that the gods tie an invisible red cord around the ankles of those that are destined to meet one another.
Other cultures, among which Jewish and Hindu, wearing a red string on the wrist – usually a wool thread – serves the purpose of protecting from bad luck or evil influences.
On top of that Red itself is the colour of passion in the western world, and joy and fortune in the eastern one.
It's not only about the positive imagery, but also about the fact that there isn't "one true way" of looking at Red Threads, but a lot of diverse interpretations and interlaced, overlapping meanings.