Warning: contains spoilers for the Attack on Titan manga and anime!
Attack on Titan’s Eren Jaeger deeply feels the sting of every comrade that dies trying to save him. But can he feel physical pain when he transforms into a Titan and suffers immense damage? Is he tethered so he feels the injuries his Titan suffers?
Hajime Isayama’s Attack on Titan introduced humans with the ability to transform into Titans by injuring themselves with a set goal in mind to shift into gigantic humanoid monsters. Eren is the sole hope for Eldians to fend off another race of humans (Marleyans) who despise those with the ability to change into Titans. Eren certainly feels pain each time he chomps down on his hand to change into a Titan. But once he’s piloting his Titan do inflict injuries cause him pain?
Eren stumbles his way through learning to shift into Titan form, beginning after he is partially consumed by a feral Titan. This injury sets off his transformation. Eren doesn’t gain the ability to stay conscious while transformed until much later on after practicing the process. The after-effects of transforming include immense fatigue, leftover injuries sustained while in Titan form, as well as marks where Eren was conjoined with his other side. Eren heals while in human form discharging steam from the wound like a Titan would. Eren is plagued by thoughts of his own inadequacy and by the sight of his friends in the Survey Corps risking and losing their lives to protect him. Something he tries to make up for by abusing his Titan form with abandon killing every enemy in his path.
Eren initially can’t really remember what happens in Titan form until he gains more control through practice. When he is capable of explaining what’s going on while piloting a Titan from the nape of the neck, he says he can’t really feel the injuries. Titans heal incredibly quickly, recovering from severed limbs and gouged eyes within minutes. But if a human who can transform is cut out of a Titan they retain whatever injuries their Titan sustained. Reiner Braun successfully kidnapped Eren by biting and ripping him out of his Titan when Reiner was revealed to be the Armored Titan. Eren’s arms are severed in the process and he is left limbless for an extended period of time while his body heals. He can continue to heal as a regular human thanks to his ability to transform, but why he can heal in human form is never clearly explained in Attack on Titan.
Humans who can transform gain the ability by eating a person with one of the nine Titan powers that have been passed down for thousands of years. Eren’s Titan is the Founding Titan, called the “coordinate” by those sent to infiltrate and kidnap Eren. Eren’s father Grisha gifted his son this cursed power (by letting his son eat him), marking Eren as both savior of the Eldians and the target for annihilation by the Marleyans (not a good birthday present).
Eren is a pretty sensitive guy and spends a lot of time early in the storyline moaning about his inability to control his power but later grows hardened with hatred toward Marleyans. His intense emotional output shows he definitely suffers a lot from his Titan powers, but the pain inflicted on him doesn’t seem to have much effect. A guy who willingly gnaws on his palm regularly can get used to a bit of pain, so Eren doesn’t spend much time languishing over physical discomfort. It doesn’t seem like the injuries he gets in Titan form in Attack of Titans hurt him in human form (other than the long process of healing) but he treats it more as an inconvenience as opposed to constant agony.