Board Thread:Naruto Discussions/@comment-26367861-20161025235033/@comment-25122992-20161026191849

GunmetalDragon wrote: But do they have to be the same pair to awaken the Rinnegan? Madara said he'd take Obito's eye for himself because you need 2 eyes to awaken their full power. He said this while having another spare in his left eye.

Well, I think it was implied throughout the series that only the original wielder of the pair of eyes can bring forth their fullest potential. If we apply it to the Rinnegan as well and couple it with the statement that the eyes can show their true power only as a pair, it seems to mean that only the original owner of the eyes can awaken it when he possesses both of them.