Zig-Zagged: Fluffy chases the duo, then stops when it spots much slower prey. It catches the prey and eats it, then continues to chase them after done with its meal. It then gets tired and stops to take a nap... then wakes up half an hour later, dedicated to finding them again.
Averted: Fluffy leaves Alice and Bob alone as soon as they leave its territory.
Enforced: "We need to give the audience a sense of urgency and the thrill of the ever-lasting chase!"
Lampshaded: "What, does this thing think we're a 5-star meal or something?"
Exploited: Bob is leading Fluffy into a trap.
Defied: "Oh, those two aren't even worth it, I'll just butcher this cow instead or something."
Discussed: "Knowing our luck, he's not gonna go away 'til we kill him."
Conversed: "Ever notice how predators on TV are stubborn when it comes to food?"
Deconstructed: Fluffy keeps chasing Alice and Bob until he dies of starvation/exhaustion, which could have been avoided if he had gone after easier prey. When Alice and Bob come up on Fluffy's corpse, they lament the senseless waste of monster life.
Reconstructed: Fluffy's species is quickly dying out, and its habitat is almost completely devoid of prey. They need to pursue any morsel of food they can find, no matter what the cost.