When Nicholas and Glenn wandered into a back alley surrounded by walkers, I felt some things I hadn’t experienced in the last five seasons of The Walking Dead: Panic. Dread. And fear.

Zombies are scary again.

In the first season of The Walking Dead, the walker threat was very new and very strange. Little was known about the living dead, and how to get rid of just one posed a challenge. A single walker without legs lying prone under a bicycle evoked enough fear and intimidation to shake Rick down to his knees.

As the characters of Walking Dead grew familiar with their new surroundings and their survival skills sharpened, the fear faded.

Dozens upon dozens could be wandering in the background and it became as normal as traffic. Rick would nonchalantly garden while packs of walkers snarled just fifteen feet away.

It was during this time that The Walking Dead redefined who the real threats were. Season 3 declared that walkers weren’t the real enemy, but fellow man. The Governor, the Terminus cannibals, and the countless wanderers who betrayed trust lived up to the show’s new tagline: “Fight the dead, fear the living.”

But those threats have been dealt with. The Governor is gone, Terminus was left in ruins, and now the scattered Wolves are the threat of Season 6. But their easy takedown by Rick’s quick trigger finger and Morgan’s sick stick skills show that they won’t be a threat for long. The ones who will be around are walkers, who have made mincemeat out of Alexandria’s Red Shirts and one beloved Glenn Rhee.

After “Thank You,” it’s assured that the zombies are a legitimate threat again. They’re no longer just a consequence for making dumb mistakes or an element of nature to manipulate a la Carol freeing everyone at Terminus. Walkers aren’t target practice anymore, they are why practice is needed. Their strength lies in numbers; Rick won’t blink at a single walker, but his break down at the end of “Thank You” came from his outnumbered odds.

There are few things as terrifying as feeling helpless.