Bill’s actions didn’t come without a cost. He have saved the world, but the world he’d saved saw him only as a man who’d pushed a blind teenager to her death for no reason. He didn’t receive a hero’s welcome, but a prison sentence for murder and the alienation of his son Daniel and ex-wife Helen.
Back from the Dead
That was another consequence of Bill stopping the invasion – every death we’d witnessed over two seasons of bloodshed was reversed. Daniel and Helen were suddenly alive and well. Ash the hospital porter who’d been stabbed to death by an increasingly psychotic Sacha, was fine and dandy. Sacha never met or fatally shot Emily’s mother Sarah, so she’s out there now too. French physicist Catherine, who we’d seen killed by a ‘Mechanical’ (the name the Invaders gave to the killer robo-dogs they sent out from their ships as a first wave), was alive again. Catherine had never met and fallen for Colonel Makrani, and so had also never lost him. Her sister Sophia similarly hadn’t lost her partner Nathan, the father of her baby, because their baby no longer existed in this new reality. And so on and so on.
Bill having stopped the original invasion from ever happening though, doesn’t mean that Earth is safe. That’s because when Bill travelled back in time, he didn’t go alone. A handful of murderous, human-hating Invaders led by the ruthless Adina also came along for the ride. Bill’s Invader ally Isla was shot dead by Adina just as the ship was taking them back, leaving a clutch of very dangerous Invaders stranded in the new invasion-less reality. And thanks to Isla, Micah’s book of time travel formulas is now also in the new reality with them, if only they can retrieve it.
Adina and the Virus Threat
Adina and co.’s hatred of present-day humanity was handed down generation to generation, thanks to French psychopath Sacha – the Adam to Emily’s Eve – radicalising his descendants against his former people. Adina thinks the only good present-day human is a dead present-day human, and as such, still poses a major threat to humanity now that she’s trapped on Earth without a ship. Particularly because Adina is in possession of a vial of Bill’s virus.
In season two, Bill created a virus as a weapon against the Invaders. He tested it on Emily – who, as their ancestor, shared genetic material with them – and found that it worked. Without insulin to reverse its effects, Emily would have died and so too would the Invaders. When Emily’s brother Tom was almost killed by the Invaders, Emily recognised their brutality and agreed to let Bill use the virus in her blood to try to wipe out her Invader future-children.
Adina’s people however, knew that Bill was destined to create the Invader-targeting virus, and so broke into his lab and stole a vial of it. The plan was to reverse it so it would work as a biological weapon against present-day humans instead of their people.