David Ramsey teases a "blood quest" for Diggle in this exclusive interview with the Arrow star. It was conducted at PaleyFest 2013.
Added:
Take note, Arrow fans: Episode 18 will be a major one. Stephen Amell explains why in this TV Fanatic exclusive.
Added:
Arrow producer Greg Berlanti talks up The CW show in this exclusive PaleyFest interview, giving us an idea of what's to come.
Added:

Arrow Quotes

Diggle: I see you brought your plus one.
Ray: Nice to meet you. Ray Palmer.
Diggle: John Diggle. [whispering into Ray's ear] You hurt her, they'll never find your body. [louder] Nice to meet you!

Felicity: What's going on? Ray?
Ray: Oliver Queen is the Arrow.
Felicity: What?
Ray: I have a 140 IQ and three PhDs, but it's pretty hard to insult my intelligence, but I'm pretty sure you just did. It all makes sense now. Your, ah, sudden disappearances, your apprehension of helping me with my mission. You've been working with the Arrow this whole time.