The Talking Titan was a former member of an Eldian cult that followed "Lady Ymir" in Marley before she was turned into a mindless Titan when the group was discovered by the Marley Public Security.
Appearance: This woman appeared to be a young lady with short blonde hair (though it was longer several years prior) and bright gray eyes. Her Titan form was about 6 meters tall, had a very large head for its body size, a mouth with constantly exposed teeth, and short blond hair much like its human form. However, its body was muscular much like other Titans.
History: " However, when the cult was discovered by the Marley Public Security, the woman was taken through the streets with the rest of the cultists and Ymir herself until they were sent overseas to the border of Paradis Island where they were all turned into Pure Titans.
Story: During the 34th expedition beyond the Walls as Ilse Langnar flees towards human territory, this Titan finds her and corners her against a tree. Rather than eating her, it instead stares at her until, to her amazement, it speaks. The talking Titan speaks of her as "a subject of Ymir" and afterward addresses her as "Lady Ymir" before greeting her with a formal bow.
Abilities: This Titan was able to speak words with meaning to Ilse Langnar. It also could display emotions which regular Titans lack, such as reverence, anguish, and perhaps fear.
Source: Talking Titan (Anime), available under CC BY-SA 3.0.