It's commonly believed that Negan (Jeffrey Dean Morgan) is trying to deceive Alpha (Samantha Morton) on The Walking Dead, but it's possible that she's pulling the same trick on him. After escaping from prison, Negan crossed over into Whisperer territory, and despite having issues with Beta (Ryan Hurst), succeeded in convincing Alpha (Samantha Morton) to make him one of their own.
In The Walking Dead season 10 midseason premiere, titled "Squeeze," Negan plants the seed of doubt in Alpha's mind by trying to convince her that Gamma (Thora Birch) has switched sides. Alpha reacts in anger, but a conversation with Beta reveals that Negan's words did indeed have an effect on Alpha. Alpha orders Beta to bring Gamma to her so that she can find out for herself if Gamma's growing friendship with Aaron (Ross Marquand) has led to a betrayal. Later, Alpha leads Negan away from the others, forces him to take off his clothes, and seduces him.
Alpha had said that she wanted to "reward" him for being brave enough for having the courage to tell her what he did about Gamma, but the situation may be much more complicated than that. Alpha's complex and strategic approach to defeating the Hilltop and Alexandria is proof of the character's wisdom. She doesn't seem like the kind of person who would trust Negan so easily. Also, having had a spy of her own amongst her enemies, Alpha shouldn't be too surprised if they try to implant their own spy in her group. It could be that she's trying to keep him close so that she can use him in one of her plots.
Fans have suspected for a while that Negan has infiltrated the Whisperers just so that he can kill Alpha. This theory is supported by the actions of his comic book counterpart, who succeeded in his plan to kill Alpha. What if the TV version of Alpha knows or at least suspects what Negan has in mind? She could kill him, or find a way to take full advantage of his presence. Alpha could believe that if Negan is a spy, he'll eventually try to leave a warning for the other communities. If Alpha keeps tabs on Negan, she can use him to further her own agenda by purposely providing Negan with false information. This could be just one step in Alpha's master plan to win the Whisperer War.
If this is what Alpha's real plan is with Negan, The Walking Dead season 10 could be heading toward a big shift from the comic story. In the comics, Negan kills Alpha, which is why it may be a lot more interesting for The Walking Dead to try a different direction by having Negan and Alpha double-cross each other. If this happens, it may be up to a different character, like Lydia (Cassady McClincy), to take out the leader of the Whisperers.