Can Uchihas get Eternal Mangekyou Sharingan by exchanging their eyes?


Let's say Uchiha A and an Uchiha B both have awakened their Mangekyou
Sharingan. If A and B exchange their eyes, can they unlock Eternal Mangekyou
Sharingan?




In the Manga, only:

  * Uchiha Madara, 
  * Uchiha Izuna (Madara's brother), 
  * Uchiha Shinsui, 
  * Uchiha Itachi(Sasuke's brother), 
  * Uchiha Sasuke, 
  * Uchiha Fugaku(Itachi's and Sasuke's father) 
  * Uchiha Obito, 

Is shown to have awakened Mangekyou Sharingan (henceforth the MS). Of those 7
only 2 is confirmed to have an Eternal Mangekyou Sharingan (henceforth the
EMS), that is Uchiha Madara and Uchiha Sasuke.

**Uchiha Madara**

Madara gained his EMS after taking his brother's MS. Note that he claimed that
his brother gave it to him. Madara did not take it from him by force. When
Madara told this story, his brother was shown to be on his deathbed. By the
time Madara gained his EMS, his original eyes has lost its light, he is
practically blind.

**Uchiha Sasuke**

Sasuke gained his EMS from Uchiha Itachi. At first he hesitated in
transplanting Itachi's eyes into his. After his eyes got worse from the
extensive use of MS techniques, he agreed to the transplantation and thus
gained his EMS. Itachi's eyes were also near blind.

There are 4 points that is similar between the two.

  * **One** is that they have their original eyes evolved into MS. 
  * **Two** , they transplanted the other eyes from their brother. 
  * **Three** they transplanted their brother's eyes when their original eyes are blind or near blind. 
  * **Four** both's brothers are dead when they transplanted the eyes.

IIRC it was told in the manga that transplantation is better done between
close relative since they are more compatible.

If, only the first two conditions are necessary for the EMS then yes, any
close relative that has awakened MS can simply exchange eyes for both to
awaken EMS. If point 3 is also need to be met then they still can exchange
eyes after exhausting their eyes, making it near blind. If point 4 is also
necessary then they can't simply exchange eyes as one needs to die before the
other can transplant their eyes and awaken EMS.

