Harry, Hermione, and Ron spend a ton of screentime preoccupied with locating the real version of the locket that Harry and Dumbledore found at the end of the last film. And this isn't just because the locket is pretty, or because stealing a prized possession of Dolores Umbridge's would make anyone smirk.

The locket contains a teeny tiny bit of Voldemort's soul. And don't be fooled by size here; there's a lot of evil crammed into that little necklace, both literally and symbolically.

First, let's start with the literal: the locket has some serious dark magic protecting it, and it contains a piece of Voldemort, so it has some pretty serious mood altering effects. Harry, Hermione, and Ron have to wear the locket to keep it safe, but they can't wear it for too long, because otherwise their moods get really dark—especially Ron's.

The necklace draws out all his doubts about his friends and suspicions about their motivations, loyalty to each other, and secret Harry-Hermione sexual tension. The end result? The friends end up at odds with each other, and Ron ends up leaving.

But there's more going on with its significance on the symbolic level. The locket represents and embodies the whole mysterious, hard-to-wrap-your-head-around Horcrux errand that they've been sent on…with basically zero information on how to achieve their goals or tools to complete it.

When the movie begins, they just know that a guy named R.A.B. stole the real locket from Voldemort and was intent on destroying it.

Just to recap, they don't know:

• Who R.A.B. is/was
• Whether R.A.B. is dead or alive
• Whether R.A.B. has destroyed the Horcrux
• Where the Horcrux is (if it's not destroyed)
• How they'll destroy the Horcrux when they find it, without the sword of Gryffindor to help

That's a long list of questions, right?

The kids are feeling pretty anxious about the Horcrux hunt as a whole, and this first mission to find the locket brings out all their anxieties and even anger about being left with the task of destroying Voldemort without any guidance from Dumbledore.

And again, this is particularly true with Ron. Ron feels like they are on a wild goose chase with this larger Horcrux hunt, and he comes to doubt that Harry is leading them effectively.

So, when things with this first Horcrux drag on, Ron's frustrations about feeling obligated to follow Harry in the overall mission while basically zero progress is happening all come flooding out.

RON: I just thought, after all this time, we would've actually achieved something. I thought you knew what you were doing. I thought Dumbledore would have told you something worthwhile. I thought you had a plan.

HARRY: I told you everything Dumbledore told me! And in case you haven't noticed, we have found a Horcrux already.

RON: Yeah, and we're about as close to getting rid of it as we are to finding the rest of them, aren't we?

HERMIONE: Ron. Please take—please take the Horcrux off. You wouldn't be saying any of this if you hadn't been wearing it all day. 

So, the locket Horcrux both literally causes and symbolically represents all the doubts, lapses in loyalty/trust, and other not-so-nice feelings that can come up when the going gets rough.

Lucky for us, though, Harry and the gang are stronger than any stupid locket.