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

Oliver Queen is dead, eventually to be reborn as Ra's al Ghul. For now, only the Arrow, Al Sah-him, shall remain. Al Sah-him, Heir to the Demon.

Ra's al Ghul

Ray: Advanced Technology Operating Mechanism. ATOM.
Felicity: What are you going to use it for?
Ray: To protect the people of this city. And I want you to help.
Felicity: Why does this keep happening to me?