A is there as part of a major theme of HV through the series, who among us could become a killer and why. What is free will? There's a long spectrum of killers, TLS at one end, Alison at the other, and Becky, who killed herself. Catherine; who wanted to kill TL, had motive and opportunity, didn't.
We can understand or even forgive Alison, Becky, because we know their story. The full story of what makes a psychopath like Tommy, is barely sketched in.
I thought this weeks portrayal of TL was an utter masterpiece. You see him as superb physical specimen cresting the hill ; leaps off the bike; embraces the land like a king. In that moment he has literally escaped his past and is free, the world at his feet. . For the briefest moment fate hangs in the balance... then it's all downhill. He's back in a tiny room, losing it, disintegrating. He says to Ryan " I love you, you're all I've got".. and we know he has nothing at all. He's already lost Ryan. Its written all over Ryan's face.