It seems that Varian can interact with the memory. Whether it's Luca's mind constructing what he thinks would happen, or a realistic interpretation of how things would go, it does seem that the memory diverges from it's original path as Ercole's attention shifts to focus on Varian. He sneers, eying Varian up and down.

"Yes, yes I see," says Ercole, not getting Varian's point in the least, "You're a much more impressive monster than they are. I wonder if I'll get an even better prize if I turn in your body with the other two?"

Of course, Luca realizes. If humans offer a 300,000 lira reward for dead sea monsters, of course they'd offer something for...well, rock monsters? Whatever this guy was. Sure, there weren't any posters advertising rewards for dead rock monsters like the ones for sea monsters, but that's probably only because there had been more sea monster sightings. If Varian were to look around the town, he might even spot one of these posters among the murals and other imagery of humans killing sea monsters. There was even a fountain nearby depicting this.

Ercole readies his spear, and seems to be preparing to drive it through Varian.

"Um...sir? I think he's really going to do it!" Luca cries out, trying to warn the mysterious stranger before he gets himself hurt.