User blog comment:Milks26/Clarke & Roan/@comment-26247132-20160207033547/@comment-26564154-20160207161229

One Ice Nation character was already introduced in The 100 season 3 premiere. Prince Roan, played by Zach McGowan, is an outsider. Initially thought of as a villain, it turns out Roan isn’t as bad as fans believed. Collider interviewed the actor, who hinted what Roan really wants.

''“The Ice Nation is a pretty brutal place. They breed war heroes. The relationship between mother and child, in that world, is a little bit different than it is in our own society. “But, no one really likes being a disappointment to their parents and their family. More than anything, he just wants to return home.”''

From 'Zach's' statement above it appears that he's mother was the one who banished him from IN and not Lexa. And since Lexa commands all 12 clans she can override the Mom's decision. Hmph!! But, I still don't see how Lexa can force someone like Queen Nia to except someone she discarded.