I don't get the Umber part. There's nothing to indicate its a ruse... Umber wouldn't act alone (in the show). His concerns and need for alliance are completely reasonable from his perspective. With the Greatjon dead anyone who had "true" alleigance to the Starks in House Umber is gone. If the Manderlys and the Northern Plot come to fruition or are in any way real at all remains to be seen. There was no primer in the beginning to remind us who the Umbers were or anything so I am highly skeptical of any shenanigans going on. Like, if they showed the Greatjon saying how awesome Robb Stark was back in season one. Then yeah, its totally a ruse. But they didn't so we're led to believe that Smalljon Lord Umber gave over Rickon the moment his father died and the Wildling threat became apparent.
I mean guys, the show is subtle occasionally. But not very often.