The Greil Mercenaries are a group of Crimean soldiers in Fire Emblem: Path of Radiance and Fire Emblem: Radiant Dawn. Their work revolves around fighting local brigands and protecting villages for money. They had relatively modest objectives until they found Princess Elincia. Titania is the Deputy-Commander of the Mercenaries; she was an ex-Crimean knight, and met Greil in Gallia while training as a knight. She is deeply affected by Greil's death, and Ike, his son, suspects that she may have had romantic feelings for Greil. The staff officer and strategist of the Mercenaries is Soren. Initially, Soren was suspected to be a Spirit Charmer — one who has made a special pact with the supernatural, but he is actually Branded. Branded are beorc-laguz hybrids generally despised by both races. It was under Ike's persuasion that Greil accepted Soren into the Mercenaries. Soren states absolute loyalty to Ike.
Mist is Ike's sister and the holder of Lehran's Medallion (the Fire Emblem). Mist is one of only a few beorc with a spirit gentle enough to keep the medallion's chaotic energies in check when held in her grasp. After being left behind in battle with Rolf, she later joins because Rhys had taught her to heal. Rhys is the primary healer in Greil's Mercenaries. He joined the mercenaries about a year prior to the beginning of the game after finding Titania severely injured in a forest near his home and nursing her back to health. However, Rhys himself is physically a very frail man, and is occasionally bedridden with fevers brought on from overwork. Prior to joining the mercenaries, he stayed at home with his parents and couldn't find work because of his weak constitution.
Within the Mercenaries are three brothers, Boyd, Oscar and Rolf. The oldest, Oscar, takes the most responsibility amongst the siblings. Before joining Greil, he became a Crimean Knight so that he could earn enough money to look after his brothers. Due to his father's death, Oscar left the army, but subsequently found it difficult to support the family. The brothers were later recruited by Greil; as a result, the brothers are some of the most loyal members. The middle child is Boyd, a headstrong fighter who shares an amicable rivalry with Ike and a crush on Mist. Like Oscar, he too tries to support Rolf. Rolf is the youngest and initially the weakest of the brothers. He shares a friendship with Mist, who is of a similar age to him. He was taught how to use a bow by the Sniper, Shinon, during which time he developed a friendship with him. Despite still being young at heart, he becomes an accomplished bow-user.
The most fickle and critical in the Mercenaries are Gatrie and Shinon. Shinon regularly belittles Ike and finds it insufferable that he should be under the command of the young soldier. He seeks more challenging and prestigious opportunities for Greil's Mercenaries, who only do minor jobs. He departs from the Mercenaries when Ike becomes leader subsequent to Greil's death. After a brief stint with the Daein army, he begrudgingly rejoins the Mercenaries after learning that Ike had grown stronger and after his student, Rolf, persuades him. Gatrie's main focus on life is women; this often impacts the decisions he makes. He leaves with Shinon for relatively the same reasons as him, and later takes on the job of being the bodyguard for the Begnion noble Astrid (to have Gatrie rejoin your party, you must have Astrid talk to him). After they help him to resist a Daein attack, he later rejoins the Mercenaries on a ship that Astrid had boarded.
The newest member of the company, Mia, is a friendly and slightly eccentric person. She joins up with group when the company heads out to Gallia. Mia was captured by Daein troops and was rescued by Greil. She decides to join up with the group during Chapter 7 of Path of Radiance and stays with group. She was told by a fortune teller that she would meet her "white rival". Mia presumes that her rival is Rhys, even though he is usually sick and cannot fight.
In Radiant Dawn, most members of the Greil Mercenaries are arguably the best of their class. The only members that could rival them are possibly the Dawn Brigade upon promotion. They are perhaps the strongest and best group in Radiant Dawn.