You find a young man waiting for you on deck. He wears heavy clothing of a kind you've never seen, the colors of his tabard bold and bright.
Rekke is a mysterious young man from Lipasalis in Yezuha, a nation that's unknown to many people of the Eastern Reach due to the storms that separate the east and west. Rekke is evasive on the subject of just why he wanted to brave the storms (it may or may not include buildings being set on fire), but the end result was that Rekke and a few other missionaries were determined to travel through the storm to see what was on the other side and bring their God to the people there, but the storms ultimately destroyed his ship and killed the rest of his crew.
After surviving the shipwreck that nearly took his life, he meets the Watcher.
Rekke can't speak Aedyran, so communication with the Watcher is difficult, but he joins the Watcher as gratitude for saving his own life and to learn about the Deadfire. He proves to be quite the talkative - and mysterious companion who gets along with the rest of the crew quite well.
When you first meet him, you can talk to him in a variety of tongues, to no use. The options are Engwithan, Eld Aedyran, Vailian, Ixamitl, Ordhjóma (White That Wends), Deadfire, Rauatai, and Lembur (dwarf).
Rekke is found at a flotsam, which is located on the world map. You can either leave him at sea or bring him on your ship to recruit him to your party. He can be a fighter, a brawler (fighter+monk), or a brute (fighter+barbarian).
Rekke starts as a standard sidekick with very little dialogue but after 30 in-game days, he starts to learn Aedyran. You will then be able to talk to him like a standard companion, and you can ask him about his opinion on the other companions and sidekicks.
After he learns Aedyran, you can show him the Strange Tablet, which he will translate from Seki:
Prince of the Heavens shall be fed only young grasses grown on the hills of Lipasalis. He shall be curried morning and night with a brush made of the bristles of boars fed on golden root...
He shall be given to only the handsomest of mares of the most feisty temperament, for he grows bored unless challenged. And when he is sad, he shall have in his ear whispered only the sweetest praise.