Slade promised to kill the person Oliver loves the most and he's holding Felicity hostage. He's seen what we've seen as shown in this photo from the Arrow Season 2 Finale, "Unthinkable."
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We'll learn if Laurel survives a Mask's hands in the Arrow Season 2 Finale, "Unthinkable."
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Slade seems to be making a point in this photo from the Arrow Season 2 Finale, "Unthinkable."
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Canary has a gun and here's betting she's not afraid to use it in this photo from the Arrow Season 2 Finale, "Unthinkable."
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So Slade finally gets off the couch? Something tells me he might wish he had stayed in the comfy chair. Arrow doesn't look happy in this photo from the Arrow Season 2 Finale, "Unthinkable."
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Oliver is still unsure, but we know that the Arrow is filled with light in a dark world. This is a photo from the Arrow Season 2 Finale, "Unthinkable."
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Arrow isn't holding back his feels in this photo from the Arrow Season 2 Finale, "Unthinkable."
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Arrow takes aim in this photo from the Arrow Season 2 Finale, "Unthinkable."
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Arrow Season 2 Quotes

Sara: That's not true. I wanted to kill Roy because that's what I do. That's who I am. I spent six years in the darkness and I looked into the eyes of the devil and I gave him my soul.
Oliver: I can help you get it back.
Sara: No. You deserve someone better. You can harness that light that's still inside of you, but I'm not that person and I never will be.

Laurel: Helena, you don't have to do this.
Helena: Yes, I do. Because once you let the darkness inside, it never comes out.