[Spoiler] Dina is the first wife of Grisha Yeager. One year after their marriage, she gave birth to their son, Zeke Yeager.
Dina is of royal blood as member of the Fritz family. When the 145th Fritz King built the walls and decided to move to the island Paradis, her branch of the Fritz family stayed behind due to disagreements with the King's choice. She joined the Eldia Restorationists on Marley, in order to revive the pride and power of Eldia. In this group, she also met Grisha Yeager, whom she eventually married. She gave birth to their son, Zeke Yeager. At the age of 7, their son reported his parents to the Marley government. As a result, all the Eldia Restorationists were sent to Paradise. Sergeant Major Gross injected Dina with the Titan serum and she was thrown off the Borderline wall to Paradise, as Grisha, in horror, watched his wife turn into a Titan. [/Spoiler]
[Spoiler] After the Colossus Titan breaches Shiganshina District in Wall Maria, many Titans proceed inside and among them is Dina. She embarks inside the town and is seen by Eren and Mikasa as they try to free Carla Yeager, who is trapped under the debris of their house. Though Hannes initially comes to their aid and decides to face Dina, he stands catatonic in fear of her frightening appearance. After he realizes that he is too afraid to face it, he opts to instead take Eren and Mikasa to safety, leaving Eren's mother behind. Afterwards, Eren witnesses Dina pull Carla out of the debris, as it proceeds to violently incapacitate her and devour her shortly thereafter. [/Spoiler]
[Spoiler] Five years later, after Eren had already joined the Survey Corps, Dina appears again before Eren and Mikasa outside the Titan Forest during the military's pursuit of the Armored Titan. After killing Hannes, who was protecting Eren and Mikasa before he was devoured, the Titan reaches out for Eren, who punches its hand. This activates powers Eren was previously unaware of, and seemingly gains control over the surrounding Titans. The ones that are under his control proceed to kill Dina by ripping her to shreds and devouring her, avenging the deaths of Carla and Hannes. [/Spoiler]
(Source: Attack on Titan Wiki)
