Omegaverse's marking system is the whole point of its tension, honestly. It's less a simple love bite and more a permanent, supernatural brand that says 'owned' in the most primal way. In most stories I've read, an Alpha bites an Omega during a mating cycle or a heat, specifically at the scent gland on the neck. That bite injects the Alpha's enzymes or whatever into the Omega's bloodstream, and it forms a biological and psychic bond.
It's not just a hickey; it's a one-way or mutual tether. For the Omega, it can mean their body recognizes only that Alpha's scent, their heats become synchronized or dependent on that Alpha, and they might experience physical pain or distress if separated. For the Alpha, it often triggers intense protectiveness and possessiveness—their rut cycles might also lock onto that Omega. The real drama comes from non-consensual markings, mistaken markings (like during a drugged heat), or when a bond is rejected.
I think what fascinates me is how authors use it to explore consent and autonomy in a heightened setting. A 'true mate' bond might be fated and blissful, but a forced marking is pure horror. The aftermath—characters trying to break a bond, or living with one they hate—is where the real angst and potential for healing arcs come in. It's the ultimate 'enemies to lovers' accelerant, or a tragic twist in a revenge plot.
Some subversions are interesting too, like Betas being able to mark, or Omega-on-Alpha markings. The mechanics vary by author, but the emotional core is always about power, belonging, and irreversible choice.