Negan could rub off on Daryl, especially if he’s in as bad a place emotionally as Norman Reedus has hinted.
He grew more hopeful and open with Beth in Season 4, then came around to the plans for bringing new people into Alexandria after hanging out with Aaron for a while.
Daryl started out the show as a mini-Merle, then slowly began to become a leader as he bonded with Rick.
Given Daryl’s history throughout the years on The Walking Dead, Negan may have picked the perfect person to try and twist into an ally.