Gaidal Cain, being bound to the Wheel of Time, is periodically spun back into the pattern. His incarnations take various forms, all of which share common themes. Most notably, he fights with two swords, and stories of him also include Birgitte Silverbow, his fated lover. Though not always the case, many of his incarnations become stories and legends told by later generations. Between incarnations, he resides in Tel'aran'rhiod with Birgitte, and presumably with other Heroes of The Horn. His appearances are usually limited to appearing out of sight of, or behind, visitors to the dream world, in order to reprimand Birgitte for disobeying the precepts that forbid meddling in the physical world.
Gaidal is romantically linked with Birgitte Silverbow when he is spun out by the wheel. At first meeting, the two usually do not get along well, with emotions ranging from dislike to hatred. Over time, they invariably become attracted to each other, often falling in love.
Outside of legend, in Tel'aran'rhiod, Gaidal and Birgitte are also romantically involved, though the details of the relationship are not clear.
Most information on Gaidal's appearance comes from experiences in Tel'aran'rhiod, and it is unknown how closely that form matches his incarnation in the physical world. Some tales called him beautiful, at times as beautiful as Birgitte. In contrast, more recent witnesses described Gaidal as an ugly, "lump-faced" man, being surprisingly short of height. In both legend and Tel'aran'rhiod, he is seen carrying two swords. He is swarthy.
In one life, after what was called the battle of Lahpoint Hills, Gaidal was inflicted with a horrible head wound that affected his mind. Birgitte, then known as Jethari, took Gaidal and traveled into the Tower of Ghenjei with him in hopes that the Finn would heal him. Sadly, neither of them survived, the Finn killing them both. 
Theories on current whereabouts
Birgitte tells Nynaeve that Gaidal Cain has been missing from Tel'aran'rhiod for some time, and claims that he has been spun back into the world. In response, several fan theories have attempted to determine the current identity of Gaidal Cain. A few of the more famous ones are as follows:
- Gaidal will be the as-yet-unborn child of Elayne Trakand and Rand al'Thor.
- Mat's ten-year-old orphan ward, the famously ugly but curiously charming Olver, is Gaidal.
- Robert Jordan stated that Olver is not Gaidal Cain.
- Jur Grady and Sora Grady's son is Gaidal. The infant is briefly mentioned in Towers of Midnight, Gadren Grady. He is currently living at the Black Tower, and seems a likely candidate, matching both the time lines and the description. The boy's own father admits that he's a very ugly child.
- However, being around 4 years old (by Rand's estimation) during Lord of Chaos would seem to make Gadren far too old.
- Gaidal Cain simply hasn't appeared yet.
- However, Brandon Sanderson has stated that he knows who Gaidal Cain is.
- He won't appear.
- Or, if he does appear, he will be a youth or infant, and also somewhat irrelevant.