This is so important. Body language says so much, and in this scene (and basically the entire finale episode) speaks volumes.
There is no imbalance of power between these two. They both lean on each other. We’ve seen it before, and we are still seeing it in Season 4; these two are better when they are together.
And it’s not in an unhealthy way. They are their own people, with their own lives, and they aren’t attached to each other.
But when push comes to shove, they are supporting each other, working as a true team and protecting each other. Even though Stiles is dying, he still steps in front of Lydia, and she lets him and they just flow together. In the finale, they acted as one person.
And that is why no matter what the creators or cast of this show say, Stydia is the true power couple.