Eren, the main protagonist of Attack on Titan, starts off with little to no knowledge of fighting and merely brawls his way through situations. More often than not, this ends up with him severely injured. As the story progresses, he cleans up his striking under the tutelage of Annie Leonhart and evolves his grappling by learning from Reiner Braun.
Because so many grappling techniques are shared among different grappling styles such as judo, Brazilian jiu-jitsu, sambo and wrestling, it's hard to pin a unique style to Eren. The most prominent display of Eren's grappling is in the manga, where Reiner and Bertholdt attempt to escape from the walls after being outed as the Armored and Colossal Titan, respectively. During Eren and Reiner's fight, Eren is able to set up a double-leg takedown off of Reiner's straight, a typical counter seen in MMA. While an opponent is throwing a punch, their hands are raised high for the punch and protection of the face, while leaving the entire rest of the body open, making it a prime opportunity for a takedown. The takedown off a punch is also especially effective in that the level change (crouching down and lowering the whole body to change the height of your head and body) acts as a bob in boxing, getting the head out of the way quickly by lowering the head but in this case also allowing for offense. Interestingly, although it appears that Eren is shooting in for a double-leg, he actually utilizes Annie's arm-triangle toss, potentially because Reiner's right arm is extended and being successful with this throw would give Eren a much more advantageous ground position than the double-leg would offer because of the extra control of the head and arm. The arm-triangle is a blood choke in which the attacker's arm is wrapped around one side of the opponent's neck and the opponent's own shoulder is used to choke the other side of the neck, effectively cutting off carotid circulation. Most commonly, the choke is applied from a side control position, where the attacker is on top with his/her entire body off to one side of the opponent, who is on his/her back. The typical double leg targets the lower half of the opponent's body, leaving the head free and arms ready to defend or position for a reversal/submission attempt.
Unfortunately, Eren is unable to maintain top position with this takedown and is reversed onto his back and into full guard by Reiner. In Brazilian Jiu-Jitsu and other submission styles, full-guard is ground position in which the practitioner is on their back with their legs wrapped around the opponent's body. Surprisingly, this position offers several offensive and defensive options compared to the top position while in guard. Because Eren maintains control of Reiner's right wrist, he is able to lock in a triangle choke by wrapping his right leg around Reiner's neck and using his leg to press Reiner's shoulder into the neck, similar to the arm-triangle choke except using legs instead. The triangle name comes from the the shape of the legs formed from putting one leg's ankle under the other's knee, forming a triangle shaped gap in between the legs.
|Eren's triangle to armbar transition|
The next grappling sequence is a beautiful transition by Eren from the triangle choke into a belly-down armbar. To do this, Eren unhooks his legs, releasing the triangle and slaps his left leg across Reiner's face while turning face-down, keeping control of the wrist and forearm. The armbar is a submission hold originating from Judo (juji-gatame) where the opponent's arm is hyperextended at the elbow by the attacker using their hips as a fulcrum. A devastating move as failure to tap out can lead to the elbow's tendons and ligaments being severely injured and in extreme cases, broken forearms as famously seen when Frank Mir snapped Tim Sylvia's arm in half using an armbar. This effect is seen much more dramatically in Attack on Titan as Eren rips Reiner's arm off using the armbar.
|Reiner's blast double|