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

Whoever you fear, fear me more!

Arrow

Malcolm: Oliver, I know I wasn't there for Tommy, but I see Thea as my chance for redemption.
Oliver: You turned my sister into a killer and then you put her into the cross hairs of one of the most dangerous men on the planet.
Malcolm: And you won't believe me, but I did so with a heavy heart and expecting a different outcome.
Oliver: Ra's is going to come for me and he will learn the truth about Sara, eventually.
Malcolm: And then he will come for Thea. And me.
Oliver: That's why I have to kill him.
Malcolm: You couldn't before.
Oliver: This time I will have you to train me.
Malcolm: Only the student will have hope of defeating the master.