N7

Shepard: What? Where am I?
Catalyst: The Citadel. It is my home.
Shepard: Who are you?
Catalyst: I am the Catalyst.
Shepard: I thought the Citadel was the Catalyst.
Catalyst: No. The Citadel is part of me.
Shepard: I need to stop the Reapers, do you know how I can do that?
Catalyst: Perhaps. I control the Reapers. They are my solution.
Shepard: Solution? To what?
Catalyst: Chaos.
Catalyst: The created will always rebel against their creators.
Catalyst: But we found a way to stop that from happening. A way to restore order to the next cycle.
Shepard: By wiping out organic life?
Catalyst: No. We harvest advanced civilizations, leaving the younger ones alone.
Catalyst: Just as we left your people alive the last time we were here.
Shepard: But you... killed the rest...
Catalyst: We helped them ascend. So they could make way for new life, storing the old life in Reaper form.
Shepard: I think we'd rather keep our own form.
Catalyst: No. You can't.
Catalyst: Without us to stop it, synthetics would destroy all organics.
Catalyst: We created the cycle so that never happens. That's the solution.
Shepard: But you're taking away our future. Without a future, we have no hope.
Shepard: Without hope, we might as well be machines, programmed to do what we're told.
Catalyst: You have hope. More than you think.
Catalyst: The fact that you are standing here, the first organic ever, proves it.
Catalyst: But it also proves my solution won't work anymore.
Shepard: So now what?
Catalyst: We find a new solution.
Shepard: Yeah, but how?
Catalyst: The Crucible changed me. Created new... possibilities. But I can't make them happen.
Catalyst: I know you've thought about destroying us.
Catalyst: You can wipe out all synthetic life if you want.
Catalyst: Including the Geth.
Catalyst: Even you are partly synthetic.
Shepard: But the Reapers will be destroyed?
Catalyst: Yes, but the peace won't last.
Catalyst: Soon, your children will create synthetics, and the chaos will come back.
Shepard: Maybe...
Catalyst: Or do you think you can control us?
Shepard: So The Illusive Man was right after all...
Catalyst: Yes, but he could never have taken control, because we already controlled him.
Shepard: But I can...
Catalyst: You will die. You will control us, but you will lose everything you have.
Shepard: But the Reapers will obey me?
Catalyst: Yes.
Catalyst: There is another solution.
Shepard: Yeah?
Catalyst: Synthesis.
Shepard: And that is?
Catalyst: Add your energy to the Crucible's.
Catalyst: Everything you are will be absorbed, and then sent out...
Catalyst: The chain reaction will combine all synthetic and organic life into a new framework. A new... DNA.
Shepard: I... don't know.
Catalyst: Why not? Synthetics are already part of you. Can you imagine your life without them?
Shepard; And there will be peace?
Catalyst: The cycle will end. Synthesis is the final evolution of life, but we need each other to make it happen.
Catalyst: You have a difficult decision.
Catalyst: Releasing the energy of the Crucible will end the cycle, but it will also destroy the mass relay's.
Catalyst: The paths are open.
Catalyst: But you have to choose.