Jack mentions that the Parasite he is hunting is a member of the Trickster's Brigade. The Trickster is a member of the Pantheon of Discord who altered the histories of individuals in order to change the overall timeline for the worse and feed off the energy caused by the chaos. The Trickster was a recurring villain on the Sarah Jane Adventures where he consistently targeted the Doctor's oldest companion, Sarah Jane Smith.
A different member of the Tricksters Brigade previously appeared in the Doctor Who episode "Turn Left" where the the creature attached to The Doctor's then companion Donna Noble in order to change her timeline.
Jack: You should save your money, Angelo Colasanto. Next couple of years, earn as much as you can. Save it all up. Because you're going to need it, bad times ahead.
Angelo: Why? What's going to happen?
Jack: Oh. So many things. Don't worry, it gets better. Then it gets worse again.
Angelo: You talk funny.
Jack: I'm a very funny man.
Jack: What are you looking for? I mean, in America.
Angelo: Speed. Change. New things. People moving so fast they're not looking at me, so I can move faster on my own. Faster than anyone.
Jack: Spoken like a true American.
Angelo: Where are you from? American visa, British passport.
Jack: A magical island called Torchwood.
Angelo: What does that mean? You keep saying things that don't make sense.
Jack: Forgive me, Father, for I have sinned. So many times. And that's just today. It's been about, oh, 700 years since my last confession. Where do I start? How about the triplets? Or the naked circus? Or that Sapphic leapfrog jamboree?
Young Priest: The Volstead Act makes an exception for sacramental wine. And the brothers upstate produce more than we can use.
Jack: The extra income feeds a lot of widows and orphans, I'm sure.
Young Priest: Yes. We're doing this entirely for charity. Every last cent.
Angelo: It's not very good.
Jack: It's the blood of Christ, Angelo. I'm sure it's good enough.
Gwen: I don't remember. Just east.
Jack: Did they say get on the Ten going east? Or on the eastbound 10 Freeway? Or what? If they said highway, they could be from back east. If their grammar was wrong, it could mean that English is not their first language.
Gwen: I didn't notice anything wrong with it.
Jack: You're Welsh, you wouldn't notice if the vowels were missing.
Gwen: Button it!
Angelo: Besides, I always hoped... if God is love, maybe He loves me, too.
Jack: That's blasphemy.
Angelo: I think that's Christianity.
Jack: It's a species of brain spawn treated as vermin on more than one hundred and fifty planets that I know of. And valued as dinner one other. they taste like oysters.
Angelo: You did not.
Jack: I had to be polite.
Jack: I came back, Angelo. I came back for you. Believe me, I have never done that before. I--I even got us that same old room.
Angelo: You came back for me?
Jack: Yes. Yes I did. You don't know whether to hit me or to kiss me, do you? Come on, you can try both.
Gwen: What's the most beautiful thing you've ever seen? Not just on Earth.
Jack: I'm not doing this, I'm not giving final speeches.
Gwen: Understand me, anywhere in the universe.
Jack: I saw a firebird once. A tiny little thing, even smaller than a humming bird. Literally made of fire. It only lives for a minute. It blazes different colors. It sings. It gets so bright you have to close your eyes. And when you open them, it's gone. But the image stays behind your eyelids for longer than it was alive.
Original International Air Dates:
Canada: August 20, 2011 on SPACE
United Kingdom: August 25, 2011 on BBC One
Germany: August 18, 2012 on RTL II