The most sought-after vore practitioner, the role of predator can be equated to the role of a dominant top in BDSM terminology in many ways.  (This shouldn't suggest that the 'bottom' prey should do nothing but receive in vore scenes, but there are points past which the prey's interaction with the predator becomes extremely limited!)

In most scenarios, the predator is in control, whether the role-play scene in question is consensual or not.  The 'unwilling pred' isn't terribly common, and usually manifests as a restrained predator force-fed prey.

Like dominants, predators are outnumbered by prey, and are always in demand.  While on the surface this may seem like a positive thing for the predators (all you can eat, able to pick and choose) the truth is the constant waves of requests for play received by anyone who identifies as predator to a sizable online community can drive one into a more reclusive state, or even force them to change their visible role, to ease the flood of attention.

Predators may be as varied in their motivations for devouring others as prey are for wishing to be devoured.  Domination of smaller and/or weaker creatures is an obvious one, but at the other end of the scale are those who enjoy swallowing their friends and lovers simply to embrace them in the most complete and intimate fashion imaginable, protecting them like no mother could hope to after the first 9 months.  In between are motives like possessiveness, where storage vore comes into play, greed for weight-gain, sadism for long detailed digestion scenes (also present in very realistic vore role-plays, not just for sadists) and of course eating entire beings tends to be excellent fuel for scat fetishists.

Sex may be an integral part of a vore scene for a predator, but for others it's intentionally absent, reinforcing the idea that the prey is nothing special at all: just food.  Sex becomes more inevitable with other-orifice vore such as anal and genital vore, of course.

Predators hunt, seduce, trick, or simply welcome their prey.  This depends largely on the predator's personality, but also their species, and even their mood.  Barring flukes like xenophilia, a hideous spider is not going to have a lot of luck with seduction.  An obese bear whose stomach prevents him from budging isn't going to be going hunting anytime soon.

Levels of realism and continuity in scenes vary between individual predators.  One predator may eat someone half their size, and gain a tremendous amount of weight from it.  If they lose the weight, they'll be sure to mention how much work it was to shed the pounds.  If they keep the weight, they may brag about it, show it off, or even complain about how 'so and so' ruined their figure.  (Sentimentality is something else that varies wildly from character to character.  Some feel regrets, some shed tears, others laugh when their lover's earring shows up in their toilet bowl two days after.) Others will eat whomever they please, and treat it as non-canon for their character.

There is a lot of community interest in female predators, to put it mildly.  The giantess phenomenon is female domination, macrophilia, vore, unbirth, and crushing all rolled up into one genre.  The female dominatrix is a very popular figure as well.  Plainly there are plenty of people looking to be dominated by women, and the most thorough domination possible is through vore.  Dedicated predators who are also female receive even more of an avalanche of attention than the male full-time preds.  Women are already seen as 'devouring' figures, given the nature of their genitals.  They receive, they swallow.  What happens when they're not satisfied with what you give them?  They'll take more until they are!

Non-sentient predators, either non-sentient animals or even inanimate objects, are less common but far from unheard-of.  Pure animals are the ultimate in uncaring predators, devouring prey solely for food, for survival, taking no pleasure in it other than the contentment that comes from a full stomach.  With inanimate objects it's a wholly alien experience, and details would of course vary wildly depending on the object. 

[There are as of yet no authoritative publications from academics on the subject of vore as we know it, only on the loosely-related subject of cannibalism, so I rely on my identity as a vore fetishist for over a decade, author of many erotic vore stories, and frequent vore-scene role-player to lend authority to my definitions.]