Dwight had been growing ever more restless with Negan's leadership on The Walking Dead, but in "Something They Need" he took real steps towards defying Negan for the first time. After spotting Rosita outside the Sanctuary walls at the end of "The Other Side," Dwight returned with her to Alexandria, offering to help with the upcoming war against Negan. But can Dwight be trusted on The Walking Dead?
Rosita clearly had her doubts, because she had Dwight locked in Alexandria's lone cell while waiting for Rick and the others to return from their mission to Oceanside. None of the other Alexandrians seemed thrilled to see him either: Daryl immediately tried to violently launch himself at Dwight, and who could blame him? Dwight may have had his own private doubts, but he had been playing the part of Negan's right hand man for so long that he'd gotten really convincing.
The episode finished with Rick pulling a gun on Dwight and telling him to kneel, making it clear that there wasn't a lot of trust there. He might have been willing to listen to what Dwight had to say, but that didn't mean Rick would believe him. However, if the comics were any indication, then Dwight definitely could be trusted.
Though the circumstances were different, in the comics Dwight also decided to defect from Negan and the Saviors. However, instead of having a solitary meeting with Rick back at Alexandria, Dwight made a connection with Ezekiel first. When Rick had his very first meeting with Ezekiel, shortly after Glenn's death, Dwight was already there, ready and willing to change sides.
Dwight worked as a double agent, pretending to be on Negan's side but really reporting back to Rick and Ezekiel. Then when the big battle was finally upon them, Dwight was able to trick Negan into thinking Rick was dead, giving Rick the upper hand and element of surprise he needed to take Negan down. After Negan was imprisoned, Dwight continued to be a useful ally, first by leading the Saviors and then by relocating to Alexandria.
While Dwight might not seem totally trustworthy in the show, the comics made it clear that he was someone Rick would be able to count on. It may take time to build a more lasting relationship between Rick's people and Dwight, but sharing a goal is a good way to start: Dwight wants Negan dead at all costs, and right now that's the most important thing.