Herons are Laguz who can perform the sacred magic of galdrar. The royal herons have white wings, while common herons have darker blue or brown wings (in the case of Sephiran, he has black wings). Long before the events of Fire Emblem: Path of Radiance, the Heron Tribe lived in the Serenes Forest. The Serenes forest was later burned down by Begnion citizens, after the Herons were blamed for the assassination of the Begnion apostle Misaha, and are on the verge of extinction by the start of the game, their population reduced to the single digits. Herons are known for their ability to see into peoples' hearts and read their emotions.
It is revealed in Path of Radiance (via a support between Ike and Reyson) that herons are physically affected by the chaotic way of war, due to their sensitive and orderly nature. This influence upon them is so extreme, that they are unable to use their regular emotion and mind-reading abilities near a battlefield. Also, Reyson implies that herons are incapable of handling "raw meat, cold fish, insects", as such foods will make them feel sick, though a part of that may be the mere quantity of food that Reyson consumed. By the end of the Tellus series, the royal herons are the last herons alive.
The higher-level a heron is, the more galdrar they will have access to. Each playable heron has certain advantages and disadvantages on the battlefield. Reyson is the least frail and has some of the best mobility (due to Canto and a higher amount of movement points, in addition to being the only flying heron outside of transformation), but can only refresh one unit a turn until he transforms, in which case he can refresh all four adjacent units. Leanne can refresh two units to either her front and back, or to her left and right, and is restricted to this number while transformed (as compared to her brothers, who can apply Vigor to all four units around them while in bird form). Rafiel can always refresh four units; however, when transformed, he does not get increased movement nor canto, and is the most vulnerable to damage.
The Herons have many uses, especially in Radiant Dawn, via their various galdrar: Vigor, Bliss, Sorrow, Valor, and Recovery. Vigor is a spell which allows a unit that has already taken its turn to take another turn. Bliss will boost a character's Biorhythm from anything directly to "Best". Sorrow will lower an enemy's Biorhythm to "Worst". Valor fills up a laguz's transform gauge. Recovery fully heals another unit. Herons cannot fight, but they may attack through use of a Spectre Card, Reaper Card, or Daemon Card. This strategy, while fun at times, is not recommended due to the low magic caps that the herons in Radiant Dawn suffer from.