Did the Alpha Speak?
When the Alpha on the causeway gets put down by the watchtower to save Jamie and Spike, just as it’s impaled and falling, it sounds like it shouts “NO”. Could that have been the Alpha’s remaining humanity briefly overpowering the rage in its final moments as it realised it was about to die? Especially considering Samson says “moon” in the Bone Temple just before Kelson was about to inject and put him down.