Roy Harper first showed up in Arrow Season 1 "Dodger" as a street-wise kid from The Glades when he stole Thea's purse. The two discovered they had a lot in common despite their economical differences and formed a relationship. 

During The Undertaking, Roy rose to the challenge of helping his city and has never looked back. The Arrow now uses him as an informant in an attempt to keep him from riskier pursuits. Roy works at Verdant with his girlfriend, Thea Queen.

Roy Harper/Arsenal Quotes

Thea: Well, you know us Queen women. Nothing gets to us.
Roy: Then you must take after your dad.

Lance: Thanks. It's been a while since I arrested you. I had forgotten how good it feels.
Roy: I was working for... him.

Arrow Quotes

There is a prophecy. The man who doesn't perish at the blade of Ra'a al Ghul will become Ra's al Ghul. Ra's al Ghul doesn't offer, he orders. Oliver! Don't delude yourself into thinking you have a choice.

Malcolm

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!