The red thread of fate is an East Asian belief originating from Chinese legend and is also used in Japanese legend. According to this myth, the gods tie an invisible red string around the ankles of those that are destined to meet each other in a certain situation or help each other in a certain way. Often, in Japanese culture, it is thought to be tied around the little finger.
The two people connected by the red thread are destined lovers, regardless of time, place, or circumstance. This magical cord may stretch or tangle, but never break.
(Source: litquake, via hopeisbroken)