Power of the Titans

"Are you a human being or a Titan?"

- Kitz Weilman to Eren Yeager

s are specific humans in possession of the "Titan's power" (巨人の力), which allows them to transform into Titans. Unlike regular Titans, they are able to control their regular form and retain their human intelligence. It is often noted that Shifters are far more powerful than regular Titans and sometimes display abilities unique only to them.

Description
In order to transform, they must suffer an injury that draws blood (often self-harm, as shown when Eren Yeager bit his hand to protect Mikasa Ackerman and Armin Arlert, and when Annie Leonhart stabbed her finger with a blade from the inside of her ring) while having a solid goal or belief in mind at the moment of injury. However, being injured by another person is also sufficient, such as when Mikasa brutally wounded Reiner and Bertolt. Once the transformation is initiated, a burst of energy is released (in some cases as a bolt of lightning), followed by the generation of the Titan body and a release of hot steam. After transformation, their human bodies appear to be in the nape of the Titan's neck, where they control their Titan bodies. Their human bodies are also merged with the Titan's flesh inside to varying extents, rendering them immobile. It is also visible that their eyes are connected within the body of the Titan, presumably for optic vision outside the body. An average height among the Titan forms is 15 meters, seen in Eren's and Grisha's Titan forms and the Armored Titan; but this can vary greatly, ranging from 5 meters of Ymir's Titan form to 60 meters of the Colossus Titan. It is interesting to notice that female Titan forms are usually shorter than the average male Shifters, with the Female Titan standing at 14 meters and Frieda's Titan form being 13 meters tall.

If a Shifter's Titan form is pushed to its limit, the human will emerge from the nape of its neck in a semi-conscious state. This is demonstrated separately by Eren, Ymir, and Annie when their Titan forms suffer defeat. But if a Shifter's Titan form is not exhausted, then its human form can partially emerge from the Titan form in full consciousness. Annie, Ymir, and even Eren have shown this ability on separate occasions.

When a Shifter uses their Titan power, oftentimes the area around their eyes is marked by dark lines for a short time after. Every Shifter with a known Titan form has exhibited this at least once, with the exception of Grisha Yeager and Annie Leonhart. The time the lines last appears to depend on the Shifter and possibly how long, skilled or how overworked they used their Titan forms, ranging from several minutes to several hours, as shown by how Ymir had the lines beneath her eyes for almost twelve hours, whereas Reiner and Bertolt only had them for a little less than five hours.

The Titan Shifters also gain the Titan's ability to regenerate, capable of vastly improved healing abilities and regenerating lost limbs even in their human forms. However, regeneration from severe injuries such as lost limbs can strain their powers and prevent them from transforming for a period of time. Both Eren and Ymir were unable to transform while recovering from their injuries, though Ymir is shown to have been able to transform within minutes of recovering. Healing for a Titan Shifter's human form takes much longer than their Titan form, as it took Eren 5 hours to regenerate both of his arms, whereas it would take him minutes to do so in Titan form. The time it takes to regenerate appears to depend on the extent of the injury and how focused a Shifter is on healing that area. Like regular Titans, the only surefire way to kill them is by attacking the weak spot in the back of their necks; although they are sometimes able to transfer their minds to the rest of their nervous system and survive even this.

It is also shown that they are not safe from regular Titans, and will be attacked even while transformed. Both Eren and Ymir were nearly devoured by hordes of Titans while transformed, and Reiner states that traveling while in Titan-occupied territory during the day is dangerous to any of them. During the battle of Trost, it was shown that Titans seem to prefer attacking transformed Shifters. The human soldiers had great difficulty drawing away the Titans, as they were somehow drawn to Eren's Titan form. This is because Titans are regular humans transformed by unknown means, and the only way for a Titan to regain its human form is by eating a Shifter.

A notable trait of the three major antagonistic Shifters is their lack of skin, and special abilities unique only to their Titans. Bertolt's Colossus Titan possesses steam generation, Reiner's Armored Titan possesses hardened armor-like skin, and Annie's Female Titan bears several abilities, most notably the ability to harden select areas of her skin and call upon mindless Titans with a scream. It is unknown how this relates to Eren and Ymir, who do not share their place of origin or purpose. Ymir displays the ability to partially emerge from the nape of her Titan form, allowing her to interact with others while still transformed. Uri Reiss also demonstrated this as well, once being almost completely out of his Titan form with the exception of his right hand. It is unknown whether this is unique to them or a feat that any experienced Shifter can manage over time.

Revelations concerning Ymir's past also suggest several important possibilities concerning the nature of Titans and Titan Shifters, as well as the existence of other Shifters. It is revealed that they do not age while in their Titan form, as Ymir notes she spent at least 60 years in her Titan form but has the appearance of a teenager. Although Ymir lacks complete and clear memory of this period, she recalls enough to describe it as an "endless nightmare". While trapped in her Titan form, she seems to have been a regular Titan that mindlessly devoured humans. Reiner and Bertolt do not treat this as an unusual case, and Bertolt notes that it was the same for them. This leads to the conclusion that the first time of using their power they lack self-determination and have only a decided goal, devour humans. In the case of all the currently known Titan Shifters, excluding Ymir, it appears that there was a Shifter present for them to devour, with only Eren, Armin, Ymir, Frieda, and Uri having the Shifter they ate being shown or mentioned.

Experiments performed on Eren suggest that Shifters are resistant, but not immune to the normal absorption that creates mindless Titans if they stay transformed for a long time. After spending one hour transformed during experimentation, Eren entered in a state of pain and eventually left his Titan body. With the the two subsequent transformations after short rests, the strength and quality of his Titan form degraded more and more, becoming smaller and less controlled each time. On the third transformation, his Titan form was less than 10 meters and his lower body remained free while his upper body began to merge with his Titan form. It became necessary to cut him loose, removing most of the tissue from the front of his skull in the process. As such, it seems that there is a limitation on how long a Shifter can remain in a transformed state before risking absorption. Similarly, it seems the longer or more often a Titan form is used and how exhausted the human within is, the more difficult the form can be to consciously control. This may cause the Shifter's form to regress to typical Titan behavior and can make them unpredictable if weaponized. The length of being transformed appears to depend on how skilled a Shifter is at controlling their Titan form, as Annie was able to transform twice into a fully formed Titan, in total altogether for almost a day minutes apart, without being absorbed, while Eren nearly lost himself.

A Shifter's ability to transform into a Titan can be transferred to a new host, should they be devoured. This allows an ordinary Titan to become a new Titan Shifter, should they succeed in devouring one, as was the case when Ymir devoured Marcel and regained human form. Hange Zoë theorizes other abilities, such as the Coordinate possessed by Eren, could be transferred to a new host in the same fashion. The Reiss family has done this method for years, by having one Reiss transform into a Titan and devour the previous Coordinate holder, obtaining their powers and the memories of the world. Zeke threatened to give Reiner's Titan armor over to another warrior should he fail in combat with him a second time, which could mean that Titan unique abilities can also be inherited by eating a Shifter; although he never specified if this was the method he would use. What is known is that Shifters can gain new powers by consuming a Titan serum, as Eren consumed a bottle from Rod's bag labeled "Armor", which gave his Titan form the power of hardening its skin at will, and could be related to Zeke's statement.

Grisha Yeager, a Shifter himself, was capable of using a syringe to turn a young Eren into a Titan which in turn devoured most of his body. Similarly, Frieda Reiss became a Titan via syringe in order to consume her uncle to become a Shifter and to obtain the Coordinate ability, as did Uri and Mr. Reiss.

It must be noted that Titan Shifters do not seem to adopt the Titan form of the Shifters they eat, as both Ymir's and Frieda's Titan appearances remained relatively the same before and after eating Marcel and Mr. Reiss, respectively. Rod Reiss also revealed that humans can choose the serum that will give them a specific Titan form, meaning they adopt the form given by the serum and not whatever form the Shifter they eat has.

However, some Titan forms do seem to experience certain changes. Eren's original Titan form just after receiving the serum was much smaller and seemingly less mature than his current form, and both Ymir's Titan form and Frieda's Titan form had emaciated bodies, different from their muscular Shifter appearances. Nevertheless, some common features remained in each Shifter's form. Both Eren's mindless Titan and Shifter form possessed exposed teeth and a lack of lips or cheeks along with elongated ears; both Frieda's mindless Titan and Shifter form possessed white hair, sneering lips, and gaunt noses; and both Ymir's mindless Titan and Shifter form possessed pointed ears, sharp, exposed teeth, and long, dark hair. This reveals that both the mindless Titan and the Shifter form of a single individual are essentially the same in all respects besides muscle mass; and at least in Eren's case, what seemed to be growing and maturing. Whether this is correlated to the aging and training of the human form, or a side effect of eating a Shifter, is unknown. It is also noteworthy that Reiner's and Bertolt's forms did not experience any noticeable change in the 5 years that passed since the breaching of Wall Maria and the next time their Titan forms were seen, despite the fact that their human forms did age, which could indicate that the aging of the human form is not the cause of the changes in the Titan form, or could be a trait exclusive of their specific forms.

According to Rod Reiss, a Shifter's power rests in their spinal cord, meaning that to gain the Titan powers, it is not necessary to eat the entire Shifter, more so just biting through the spine and ingesting their spinal fluid. Analysis of a serum recovered from Rod Reiss has also revealed that the Titan serums appear to contain ingredients based on human spinal fluid. However, it is difficult to study, because once the liquid makes contact with the air, it evaporates.

Notable Titan Shifters
This is a list of known Titan Shifters whose Titan form has yet to be shown in detail:


 * Marcel
 * Uri Reiss
 * Mr. Reiss
 * The First King

Trivia

 * Many Titan Shifters are modeled after wrestlers. For instance, the Armored Titan is modeled after Brock Lesnar and the Rogue Titan is modeled after Yūshin Okami.
 * The Beast Titan appears to be the most skilled living Shifter, as he possesses the power to mimic human speech in Titan form, climb over the walls, and create Titans that function at night. Annie Leonhart appears to be the second most skilled living Titan Shifter, sporting a variety of learned powers and moves, including selective regeneration, skin hardening, and Titan summoning. However, the holder of the Coordinate would often be the strongest Shifter, as noted by Rod. The least skilled appears to be Eren, who is still learning how to use his powers; and Bertolt, who can only move slowly, massive steam generation and possesses extreme physical strength.
 * It is possible that like normal Titans, a Shifter's remains evaporate when they perish as there was no trace of Grisha after Keith Shadis found an unconscious Eren after the latter received the Coordinate, even though in Eren's obtained memory, the remains of Grisha's lower body, arm, and clothes were left behind.
 * Titan Shifting is apparently not passed down through bloodline and the only way to inherit it is by transforming into a Titan and devouring another Shifter, as proven by how only one Reiss would be a Titan Shifter as compared to all of them and Eren, the son of the Titan Shifter Grisha, would be born a Titan Shifter if this were true.
 * In the case of Titan Shifting abilities and the Coordinate, it appears that if eating a Shifter of the same bloodline, one can access their powers and memories easier. Both Frieda and Uri devoured someone of their bloodline to gain Titan Shifting powers, and were aware of the memories the moment they awoke. However, Eren, who is not a Reiss and therefore not of the same bloodline, has only recently started to remember faint memories since he obtained his powers five years ago.