Guys she's the defender of the earth

Obviously the appeal of a kind, wounded veteran falling back in love with humanity and the universe opening up for a brilliant, but stifled woman has been obvious to me on previous watches, but I'm really enjoying what I feel their relationship has to say about humanity's relationship to the wider universe overall.

While they both feel like grounded characters with a very real, human dynamic, they also undeniably represent something more metaphorical to each other:

The Doctor is infinite and unknowable, cold and righteously violent, but also full of wonder and excitement, compassionate and self-sacrificing. He's Rose's gateway to the universe, both in a literal sense by taking her through time and space, but also by stretching her ideas of what's possible - expanding her perception of her own limitations and the effect her actions can have on people and events.

Rose, on the other hand, represents everything beautiful about humanity, even in her imperfections. She's empathetic and passionate and stubborn and curious, and cares so deeply about the rights and well-being of the individual, even at the expense of the whole. She can be infuriatingly partial and rash, but there's real beauty in how, to her, everyone seemingly small and insignificant has such desperate importance. It's a reality - that every person is a universe in and of themselves - that the Doctor has had to callous over in order to survive the Time War, and one she wakes him up to.

They both start the show similarly jaded - unaware of or apathetic to humanity's importance to any kind of greater schema - just from opposite ends. Zooming out a bit, the Doctor represents the perspective of a cold, indifferent universe, where individual humans are nothing but small, demanding blips in a much larger whole, and Rose is just an ordinary human, with seemingly nothing of real value to offer anyone outside her small circle of influence.

To me, it's a real metaphor for the depressive crisis of modern life: the oppressive, omnipresent perspective that the universe is big, vast, and uncaring. That there is no love or purpose there, just space dust and decay, and humanity will fade and die with nothing of real value being added. So you "get up, get dressed, go to work, eat chips, and go to bed" over and over and over again, all because there's nothing else. Right?

Except there isn't "nothing else." The universe is full of wonder, mystery, adventure, and joy. And it has wounds - wounds even a small human can help heal.

And every human is full to the brim with complexity, history, and meaning - each one of them containing a world of memory, thoughts, and sensations. Their lives can shape the course of reality, and each of their deaths is the death of a tiny universe.

And as both of them discover the other and realize this, they start to switch places. The Doctor struggles more and more with the decision to end even one life to save countless others, because he starts to see just what it is he's terminating, and Rose increasingly refuses to accept a bystander's role, even when faced with problems of a depth she hasn't been remotely equipped to handle.

By the end, the Doctor can't do it. He can't end a civilization to save the universe, even knowing the end won't be permanent, and that the civilization will likely die without him. He's become small, emotional - a "coward." He's a man rendered ineffectual to the universe by the depth of his empathy.

And Rose refuses to accept the life of safety and normality that he's gifted her, because, in this moment, it would require her to accept impotence in the face of a world-ending threat as well as the death of someone she loves. By now, both her and the audience see that she has so much more to offer than that - that the power and depth of her care can change time and space, as love, stubbornness, creativity and a giant truck transform her into a golden, god-like apparition of herself.

In the first season's finale, he isn't cosmically significant. He only matters because of one woman's love for him. And for just a moment, that woman is the entire universe.

It's a long and beautiful journey toward a simple thesis: humans do matter. Desperately.