omegaverse where omegas on the cusp of their heats tend to get... bitey. inflamed gums, sore jaws; nothing that can't be fixed by biting down, hard, into their partner's muscle (preferably their trapezius, but most omegas'll make do with an inner forearm or pectoral if need be) and squeezing. it's an evolutionary quirk, and not every omega feels the urge — the breakdown's about 85/15, 'bout the same percentage as people who taste cilantro instead of soap. but it's something that wasn't really... made public, when jack was coming up through the ranks. robby, too; it was just something that you did at home, did privately and kept the lid on as best you could in public.
he and robby hail from an era before teething toys were de rigueur in the privacy of one's own home, much less the workplace. jack feels every year of his age each time he spots mel placing sutures with the pendant of her chewy necklace in her mouth, or dennis gnawing absently at the silicone band of his ID bracelet while charting with the other hand.
jack's reminded how different the world they live in now is every time he spots the small scars on robby's knuckles, all old and long-healed, or the raw cuticles and the teeth grinding and the chewed-bloody lip whenever his cycle starts to ramp up — not at all uncommon in an omega of his age.
nobody'd think less of robby if he started using oral stims — on the contrary, jack's got it on good authority (dana's, specifically) that robby's ducklings think he's progressive as fuck for not blinking twice at designation accomodations in the ED — but every time jack's brought it up in the past, robby just gives him the same half-smile that scrunches up his eyes and asks jack, "why would I want any one of those toys when I could be sinking my teeth in right here?" as he slides his fingers under the neckline of jack's shirt to pet over the bite marks scarred into the skin there.