Should they follow it? Now that was a good question. Fran was fine with simply leading the group to look around. Even Locke's sticky fingers--a stick was not something she thought the Ancients would miss--was not cause for too much worry. Fran may very well come to regret leading two treasure hunters to this location, of course, but that thought was quickly disrupted by whatever was happening with Garnet's materia.
Fran tensed and felt prepared for battle immediately. This was not something that she could remember ever happening before, and that meant she was now more suspicious than she had been. She only barely stopped herself from drawing her bow. It was still too early for that.
"Tread carefully," she responded quietly. "If the necklace is reacting to something, it must be old itself." Old--Ancient even--and unpredictable. Dangerous, one might say.