Natsu stopped a ways from the two she was trailing not unable to hear them as they were speaking low but she happened to look around and see a glimpse of white. She then took another look at the second male. Ooohh. Isn't that the slippery thief Griff? She rolls her eyes sighing. Well if the Strawhat man helped Griff, he would be thought the thief's accomplice. She wondered for a moment if the Strawhat man was looking for a bounty so early in his travels. It wouldn't surprise her. She planned an alternate route and wound up behind a marine looking at the two. 
"Lieutenant. Its an honor to receive your help in this."
"Its our job yes?" She asked rhetorically with a raised eyebrow. Most knew that she didn't see it the strict 'justice' and 'criminal' as everyone else seemed to have. She cracks her knuckles thinking of possible ways to get the two out of the area. That way she could claim fault without being suspicious as she was a higher rank than these gathered here and go: 'I let them slip away from me.' And be guiltless especially if she 'chases' after them for a short while. Simple. She smiles. Sometimes she enjoyed being a marine. But those were very few and far between times mind you.