Rydia of Mist is a character from the video game Final Fantasy IV. Her name may have been intended as Lydia, but due to Japanese R/L confusion, translated to Rydia by non-native speakers of English who did not know that Lydia is an English name.
Rydia first appears as a child living among summoners in the village of Mist. Her mother summons a mist dragon to protect the village from imminent danger, but the dragon is killed by intruders, and Rydia's mother dies too.
The trespassers, Cecil Harvey and Kain Highwind, do not realize that the dragon is a summoned creature whose life is bound to its summoner's, nor do they realize that the ring they received from the king of Baron is a bomb set to go off when they arrive in the village. With Mist in flames, Rydia crying over her mother's body, and the whole place in fire-lit chaos, Kain and Cecil swear never again to follow immoral orders from their king. They try to take the distraught Rydia out of the burning village, but she is hysterical and summons a monster to fight them.
Rydia's summoned monster causes an earthquake that knocks everyone unconscious. When Cecil wakes up, Kain is gone, and Rydia is still asleep. The path back to Mist is blocked, so he takes her to the nearest town, Kaipo, to recover. At first Rydia is angry with Cecil and refuses to speak, but after he protects her from soldiers in the middle of the night, she relents and tells him her name. From that time on, she is loyal to Cecil and tries to assist him as much as possible.
After many adventures, the party is shipwrecked by a giant sea serpent, Leviathan. He takes Rydia down to the underworld where he reigns as king. Leviathan and Asura take care of Rydia, and she grows up among the summoned monsters.
Time passes more quickly in the summoned monsters' land than in the world above, and when Rydia is grown up, only a short time has passed for Cecil and his quest. Rydia returns to help the party, saving them from imminent danger. Through the journey her skills grow, and she becomes an accomplished summoner, learning to call on Asura, Leviathan and even Bahamut, the god of the summoned creatures, among many others. She also learns a good deal of attack spells.
After the adventure is over, Rydia is shown returning to the underworld to see Asura and Leviathan again, but she is also seen unchanged at Cecil and Rosa's wedding and coronation after that.
In guessing about her future, the underworld presents a problem: if she stays down there, she will age and die quickly while her overworld friends remain young. But if she stays on the overworld, she will not see Asura and Leviathan again. The ending is unclear about her ultimate choice of where to stay, or how long she spends with Asura and Leviathan before going back to the upper world (at which point she is shown as physically unchanged.)
There is also the question of her relationship with Edward Geraldine, a womanizing prince known as Edge in the English translation. Edge flirts with Rydia constantly from the first moment they meet. In return, she is sarcastic, harsh and sometimes downright mean. Many fans guess that she secretly likes him, and is only pretending to be mean in order to tease him. However, it is also possible that she simply dislikes him. There is not even one line of dialogue in which Rydia shows the slightest bit of affection towards him or relents in any way, so her reactions can also be read as genuine dislike. It is ambiguous, allowing fans to decide whatever they want about the pair.
(from the Final Fantasy IV Settei Shiryouhen):
Rydia of Mist
Height: 107 cm
Weight: 18 kg
These are obviously the stats for Rydia as a child. I have never seen official adult stats for her, and I believe that none have been released.