#alpha pact

The greatest thing about that scene -- about Lydia's entire character arc -- is that Lydia is able to grow and change without repudiating who she was before.

Far too often in modern bildungsroman, a teenager is forced to repudiate everything they enjoyed about their lives before as false and unreal. Lydia was a prime candidate for that cliché, and Teen Wolf took one look and said "No, we're not going to do that."

Lydia, at the start of the show was fashion conscious and status conscious. She was a Queen Bee of the school and she liked being the person everyone looked at and said “I want to be her friend.”  Her problem was that she felt she had to conceal or deny parts of herself in order to achieve that status. She hid her intelligence for other's egos, she kept her true feelings for Jackson at a distance and thus poisoned them, and she could be needlessly cruel and manipulative to others if she felt threatened.

I feel one of her key scenes in Season 1 was in The Tell (1x05), after her harrowing first encounter with Peter Hale, when she sits in her room and puts makeup on like its armor as her teacher praises her. While the scene shows her strength and qualities, it also underlines the danger of her refusing to relinquish control and actually experience what she goes through. Her focus on putting the façade above reality holds her back.

In Season 03A, there are three scenes where she finally allows herself to experience her own ability and thus not only grow into an adult but also to actualize her own power. The first is in The Girl Who Knew Too Much (3x09), when she comes back to the recital and talks to Scott:

Lydia: I can't. I don't know why I am the one that keeps finding the bodies, but maybe if I just stopped trying to fight it, I'd find them before it happens, maybe with enough time for someone like you to do something about it.

And then, after the scene you mentioned when Stiles comes to visit her in Alpha Pact (3x11).

Lydia: Then what do I do? I mean, I get that I’m like some kind of human Geiger counter for death ...

In both of these scenes, she's stopped trying to keep things at bay and embraced action instead, which requires her relinquishing her control over her own experiences.

It's no coincidence -- three times is a pattern after all -- that the scene you love so much is put between those two. Her mother is trying to be kind, trying to let Lydia bring up the walls around her own experience again so she can control how she is seen and how people react to her, and Lydia finally recognizes that this isn't the way to truly be what she wants to be.

BUT -- and this is one of the things that raises the scene from good to great -- the scene in Alpha Pact includes this:

Ms. Martin: But we're still gonna do your hair, right?

Lydia: Of course we are doing my hair.

Lydia had decided she's not going to pretend or hide her own experiences -- what happened to her -- giving them the value they deserve, but it's made clear that this is going to include all her experiences. She's not going to reject her appreciation of fashion, of status, of popularity that she worked for and she attained. She's still going to value the things she valued before. She doesn't have to destroy herself to grow.

As an aside, the show quite literally rejected the 'destroy the old me' cliché in Season 2 by showing it not working out so well with Erica with her super-sexy makeover and Allison with her room-destroying Dark Allison transformation. Lydia changes without self-immolation, and the show seamlessly implies that this is better.

… he really didn’t make it back, huh. Not entirely alone or himself, that is. aren’t open doors in the mind awesome?

"It's not just someone to hold you under. It needs to be someone who can pull you back, someone that has a strong connection to you, a kind of emotional tether."