Board Thread:Show-Related Questions/@comment-24670104-20150405210036/@comment-25176701-20150411023104

"Clarke: Reincarnation. That's how you became commander. How are your leaders chosen?"- After Clarke suggested reincarnation, it was Lexa who asked "How are your leaders chosen?".

"Clarke, a sky person, is the one who inferred that Lexa became Commander through reincarnation, but she still speculated on how the grounder leaders were chosen. Either way, none of it was ever confirmed by Lexa"- Good point. Thanks for suggesting it because I always thought it was reincarnation. You're right that it may not be reincarnation but something different.