Originally Posted by mr. peasant
Well, Roy Harper has quite a number of codenames - Red Arrow, Arsenal - that the writers can choose from; assuming he even appears in the show and becomes Oliver's sidekick (or some other vigilante). And while the writers have admitted they have some ideas of how to introduce the character (i.e. they haven't actually implemented any of it). Moreover, as evidenced by Merlyn and Laurel, just because they include a character doesn't mean they aren't going to retool said character.
That's true, but assuming the writers do things intentionally, there are an infinite number of nicknames Thea could have had, but they instead chose the name of Ollie's sidekick from comics. That means they intend to relate the two in some way. What way that is, we'll have to wait and see.