Sophia was captured by Bern forces and sent to the same prison cell as Cecilia, where she treated the general's wounds using her powers. Aside from that, she can see the future, though not clearly. She then leads the Alliance army to Arcadia, in order to help the people there shake off Bern's invasion. Sophia makes a brief cameo in Fire Emblem: Rekka no Ken, where she is looking for Athos and can have conversations with different members of Eliwood's army.
Though she has little background, in support conversations she speaks slowly, demonstrating her shyness. It is noted that she is very old, about one century of age. Sophia cannot transform into a dragon, even though she is half-human half-dragon, as she does not seem to posses a dragonstone.
She can form a close friendship with Raigh and can marry Roy if they have A-support in the end.
Her appearance changes little, if at all between the two games.
She makes an appearance in Rekka no Ken at Chapter 30: Victory or Death if the player visits the ruin village at the bottom right of the map. She also apparently knows Hawkeye, accidentally mistaking him for the Archsage like everyone else when you send Hawkeye to the ruins. Hawkeye asks her to tell his daughter that he will be home and she says she will.
Sophia fits under the Est archetype. She comes very late with awful starting stats, but high growths. With a large amount of training, she will get very high Magic and Resistance. She has good Skill and HP growths and decent Speed, Luck, and defense growths; yet, because of her lower starting stats, they will not get as high as fast as other characters. In addition, of all the characters under the Est archetype, Sophia is particularly difficult to train. She has very low accuracy when she is recruited, making it difficult for her to even finish off enemies. The player can train her in the arena or train her on chapter 14X. At 20/20, she will usually turn out slightly better than or equal to Raigh at best stat-wise. However, because of her low constitution, she will be slowed down quite by her Dark Tomes, though that can be compensated for with a Body Ring.
Once promoted, Sophia becomes a glass cannon, easily one rounding enemies with her high magic. However, the same goes for her with physical attacks, due to her low speed and skill, and her only average defense and HP. On the other hand, her high Resistance means that she can handle spellcasters better than most other units. Consider supporting her with Roy, Igrene, or, to a lesser extent, Fae or Raigh, to bring out her potential. Her high magic, like Lilina, makes her notably effective with Staves once she promotes. Still, as long as she has a Nosferatu on hand, she can take some physical attacks if she can hit her enemy with Nosferatu.
Sophia is Greek for "wisdom". This was the name of an early saint who supposedly died of grief after her three daughters were martyred. Sophia also appears in the phrase Hagia Sophia (which means "Holy Wisdom"), which is the name of a large basilica in Constantinople.
On the official Japanese website for Nintendo, Sophia won 10th place out of 80 in the character popularity poll for Fire Emblem: Binding Blade. The male-female vote ratio is 5:1. The voter comments seem to mostly focus on her shy, gentle, and quiet personality and the mystery surrounding her character.