Primeval, Becker, from a professional point of view, Becker will always stand by his decision to sacrifice the one to save the many. Unfortunately, his nightmares won't let him forget that the 'one' was his lover.
It's been the right thing to do. Becker knows this. He saved the world and he will always stand by the decision he has made. Because the life of one man is insignificant when weighed against the lives of billions.
No one congratulated him but no one condemned him either. It was him who killed him because he's a soldier. He can pull the trigger when the others can't, not even Matt. Matt was trained to kill monsters but Becker was trained to kill humans.
Abby didn't realise that he killed before, he knows that now, and she will never forgive him. Not for the killing itself but for being able to do it when the others couldn't.
Jess tries, she tries her best but he has irrevocably changed her view of him.
They've both forgotten that he's soldiers, that he fought in a war, that his whole purpose is to kill.
Matt and Emily understand. Emily more than Matt but whether it's because she's from a different, more violent time or because of what happened while she was wandering between the worlds is her secret and Becker doesn't ask.
Becker's at loss what Lester thinks. The man doesn't treat him any differently and doesn't mention the incident once beyond a short, "Let's hope that this won't happen again."
Lester's mask is as flawless as Becker's.
He will never tell anyone how many nights he spends awake after waking up from nightmares and prays for morning to come.
He has rarely ever had nightmares about the people he's killed before.
Now he has them every night.
It's not even a real nightmare: there are no monsters, no one's skin melting off suddenly and no dinosaur rips his arms out.
It's just the scene replaying in his mind, night after night: the pleading, the bargaining, and the sickening splash of blood, bones and brain matter against the wall.
Becker knows why he has this nightmare and accepts it as the punishment it is.
Because the man he killed to save the world was the man he loved.
"Please, Becker, please, just let me-"
"I need you step aside from the machine."
"It's just one little mistake, I can correct it if you'd just let me-" Becker grabbed him and pulled him away, making him go down to his knees.
He pulled the plug and destroyed the machine as quickly as possible, ignoring the enraged screams from the corner of the room.
"Do you have any idea what you have done? It'll take months to reassemble the data and even then I'm not sure I'll be able to rebuild it."
"You won't."
"What do you mean?"
"I can't take that chance", he switched off the safety. "I'm sorry."
"Please! Becker, don't do this. You can't just…You said you loved me! How can you-"
He pulled the trigger. Two shots in the head, one in the throat. The body slumped down, his eyes were still open.
Becker kneeled down, his face was betraying no emotion when he closed his eyes. "I'm sorry", he repeated.
The world didn't end. He had done the right thing.