Ollie listened as Mia recounted the story of how she'd stumbled upon the purple arrows. Most sixteen year-olds wouldn't have thought to be so thorough, or taken that initiative. He was proud of of her. "Good girl," he said; the fact she'd found other arrows was a key bit of information, despite the fact she couldn't get to them. Oliver knew that if it had been someone truly dangerous, someone who they should be more than just a little concerned about, they would not have left that many arrows behind, if at all.
"Whoever it is, they're not someone we can't take in a fight," Ollie said, and his confidence was unshakeable because there was zero doubt in his mind. Green Arrow was the not just an archer; he was a hunter, and he hunted down scumbags for a living. He'd been lucky (sometimes arrogant) enough to think it was a good idea to pass those skills on. Now Roy, Mia and Connor could (probably) best most other archers they came up against.
"It might take a week or two, but it's traceable. Everything leaves a footprint these days."
If Mia wasn't careful about how she steered the conversation, she might have wound up listening to Ollie go on a tangent about why the digital age sucks. And she might be trapped. Aren't dads great? It all depended on how she replied.