As Entertainment Weekly reports, Alfie Enoch didn't know what was in store for his character, Wes, when he signed on for How to Get Away with Murder: Wes, who was described as the "puppy" of the show, would ultimately end up a murderer himself.
While Alfie had speculated on whether Wes might be the killer,
[…] he didn’t even learn that Wes would strike the death blow after Annalise’s (Viola Davis) husband started choking Rebecca (Katie Findlay) until the cast gathered for the table read of the winter finale.
The actor, who had previously joked that Wes was a Gryffindor, was quick to jump to the character's defense when Entertainment Weekly suggested that “he's totally become a Slytherin for killing Sam.” Referencing the events of Harry Potter and the Chamber of Secrets, he argued,
Gryffindor could do that! The [B]asilisk has feelings, but Harry still kills that.
When asked if he thought that the reasoning for Wes being Sam's killer “was to corrupt him after coming in as this bright-eyed student,” Alfie disagreed:
I’m not sure that’s quite how I see it. People don’t come in molded by their future actions necessarily. You have a character who does something bad, but that doesn’t mean they are a bad person. Good people can do bad things. It’s an inevitable turning point, a real shift in his life in what happens next and who he’s becoming and who he goes on to become later.
He added:
Really, it has to be because of how important Rebecca is to him, but that might’ve happened a year ago. It’s not like Wes coming to law school [was the cause]; there are a lot of factors that lead up to it. That fierce protectiveness is an essential quality. [Showrunner Pete Nowalk] and all the rest of the writers managed to find a way to exploit that and to use that to do it in a surprising and dramatically interesting way.
On Wes's having killed Sam for Rebecca, he said,
To me, it doesn’t demonize him, that act. I’m not saying it’s a good thing that he does it or even justifying it, but that doesn’t denounce him utterly for me at all. He acts to protect her. He acts out of love. He acts out of need as well.
The full interview, which addresses additional questions on the show – including what this will mean for Wes's relationship with Annalise and his relationship with the rest of the Keating Five – can be read here.