Oh, good question!
Well, first of all, Odalisque isn’t omegaverse. Also, John’s behaviors and clothing in that are partially dictated by Jim. I do like the idea, though, that carriers often wear somewhat feminized clothing—at least those carriers who are ‘married’ to someone. That sounds like exactly the sort of sexualization and control that’d be imposed on them.
As for the Serviceman ‘verse, that’s a REALLY good question, and one that I think I’d feared to tackle. But you know, I really like the idea that their clothes are a bit different. That maybe they ornament themselves more than the average male.
There are no alpha females in the Serviceman ‘verse. Females are just females. I think that yes, it’s not uncommon for alphas to dress hypermasculine—power suits, or whatever serves in that niche in their particular culture. In fact, clothes could even be an indicator of an alpha’s confidence. An alpha who doesn’t feel like he needs to compete may well dress more casually, and simply let his personality and confidence carry him (you may’ve met people like this in real life!). Betas who’re putting themselves up against alphas probably also dress up that way (I haven’t talked much about betas, have I? But they’re distinctly around). Betas who don’t want to be seen as competition (and I use ‘competition’ loosely here, in a very human social/power dynamic sense) might take pains NOT to be seen as dressing up too much, so as to signify that they are not rivals to the more aggressive individuals.
For women, it would’ve been the same as in RL history and society. For omegas, though…
Okay, to figure out what omegas would wear, we want to understand a bit about how they have been perceived and the social roles they have occupied. Way back when, omegas were considered, hm, warrior helpmeets. They were obviously not women, but they were not exactly men. But they were strong and fierce and they would fight to the death for someone they loved, so back in classical times, they were the foundation of all those stories like Hercules and Aeolus, Achilles and Petroclus.
Since then, they have lost much of that dignity, and have largely been relegated to the role of…hm, mistress. But there is still a sense of them being an appropriate partner for a man in a ‘man’s world.’ Traditionally, an alpha or beta married a woman and had children with her, but historically women’s lives have been, to a greater or lesser degree, segregated. So an alpha or beta (mostly alphas—there are certain perceptions about how they have ‘needs’ and ‘rights’) might keep an omega separately, as a lover who could share the things it wasn’t appropriate for a woman to share with her husband.
In the West, at least, there has also been a tiered notion of marriage for a very long time. As the Catholic Church enacted it, an alpha or beta could take an omega as a legally recognized spouse. But if they then took a woman as a spouse, the marriage with the woman canceled out the one with the omega, her children took precedence over any with the omega, and the omega was expected to be set aside. (Not that it always actually happened that way, but this was the proper thing to do.)
These days some of that has equalized somewhat, but it does mean that omegas have traditionally found themselves in some competition with women for mates (and for keeping mates). As such, I think omegas can be expected to wear more ornamentation than your average man. I think…not skirts, but maybe bright colors. Patterns. Clothes cut to display and contour to sexual assets, whereas your typical male clothes do more to highlight strength and fitness.
John, however, I think dresses in a more masculine than average way for an omega. Partially because his background emphasized practicality, and partly because he just doesn’t want to be bothered. Jumpers are comfy and people don’t assume he’s flashing his arse at them in loose jeans.