Rules ref states the redirected challenge is "considered to have been initiated against the original opponent, but it resolves against new opponent" - this means that the new opponent cannot trigger "when a challenge is initiated against you" triggers (but the original target can) e.g. Core Eddard Stark stand reaction.
Supported by None
You may redirect 1 challenge this round.
+2 STR for Dominance
If a challenge is redirected, the player who is initiating the challenge must immediately choose a new opponent to resolve the challenge against. The attacking player may also choose new stealth targets (controlled by the new defending player) if he or she desires.