Board Thread:Spoilers/@comment-26500342-20160108000001/@comment-25176701-20160302025333

Lincoln's arc was to bridge the gap between the SP and the Woods Clan (not all of the Grounder Clans, just his), which he managed to somewhat accomplish. But things turned to hell during the peace meeting. He also helped with that in S2 for awhile before going down a different story arc (turning into a Reaper, etc.).

Lexa's arc is to change the way her people think. Hence the reason she created the Coalition (since it further proved the visionary side of her).

Lincoln isn't in a position to order anyone around because he isn't anybody's leader. Lexa's position is already being challenged and she's the Grounders' Heda, so only imagine what would happen to Lincoln if he tried to order people around (warriors aren't allowed to just do that, you know).