Gwen's lifeforce runs in Suzie's blood.
Suzie knows how this link works, this golden rope growing from the heart, reaching to the dead. So she just caught it, and now they're linked, heart to heart. Gwen couldn't break it if she tried, but she doesn't, she doesn't understand yet. Poor Gwen.
Suzie doesn't remember it was so sweet, though. Gwen's compassion seems warmer than hers. It's not only about human condition, she really pities Suzie, personally, the poor little corpse she brings back for a three-words testimony and a lot of tears.
Gwen is the kind of girl Suzie hates, she would have said not long ago. Too much feeling, too little thinking, and this disgusting happiness without even a goal in life.
But after all, if there is nothing, only the darkness... maybe there's no goal at all. Maybe happy girls who don't think are right, after all. Oh yes, Gwen is the kind of girl Suzie hates.
Suzie had a goal, the most beautiful of all : she would be the one to defy and conquer Death. She had found the only beautiful thing in the alien rubbish, the one humanity had always wanted, the most important.
The one Torchwood always wanted, too, the power to save. Yet, they didn't understand. They didn't see sacrifices were necessary, and Suzie had to compromise with the Death she hated so much, to find a haven and flee from their hate.
She knew it was temporary. They needed her. They'd found someone to bring her back.
And it had been Gwen, with her thread of light pulling her from nothingness, with her sweetly burning soul. She loves everyone and everything, and Suzie just finds it stupid and irritating. But when she feels it, connected to her, each heartbeat, each jolt of affection rings in her like a church bell.
Suzie wants to scream, why aren't you like me a little, even if she wonders secretly, why wasn't I like you a little? But Gwen should have carried on research on the glove! She can love, she can live, she should want so much to conquer death! She should have understood the only thing that matters! She took Suzie's place, and everything, why didn't she take this too?
Suzie resents Gwen so much, for not having the strength to try. Because she is so much better than her, she loves the living and the dead, and she never compromises. She could have made the glove work! She could have given life back forever! Suzie wanted this so much, and Gwen could have managed it, with training... and she would not be dying now, she would have given back Suzie's life without losing hers.
Oh, it doesn't matter, after all, Suzie will live anyway... but Gwen, Gwen ? She deserves death, for not fighting it, it's her fault... Suzie did fight it, in every possible way, so she has no be the one who lives, who never knows the darkness again!
So she carries on, and she fights, and she tries not thinking she's giving Gwen to the darkness. She doesn't want to do it. Even if Gwen is the kind of girl she hates, and took her place, she doesn't want to let her die. She just has to.
She even would have loved it if they could share this piece of life, like now. You don't need a whole life, do you, just a little piece of light, a tiny flame, and even if their heads hurt all their lives it wouldn't really matter.
But you can't be one with another person. You can break the doors between life and death, Suzie knows it now, but you can't just open them a little and take each other's hands.
Yet she tries and believes in it, as long as it is possible, as they flee together, and Suzie supports Gwen up till her last breath and a little after. They could have lived together and conquered death and saved the world, maybe.
And even after, when Gwen collapses, breathless, lifeless, there's still her lifeforce in Suzie's blood. She thought it would break, with only life to comfort her, but it's still here, the ribbon of love and light, so warm and beautiful and sad. There are still these feelings, and this way of seeing the beauty of the people and the world, which are not Suzie's, which are from poor Gwen's little flying soul.
She feels all-powerful then, and she tries to explain, that she has Gwen's heart in hers, that they are forever bound.
But they don't understand, and now she has no haven left.