Omegas can be marked by severals alphas (Keith's poor extreme omega father has 5 alphas), the mark on them can disappear (happened with Yeonwoo in the extras).
It's the alphas who can only be marked once.
Marked omegas can still be affected by pheromones of other alphas, but I think not nearly as strong as an unmarked.
And Grayson is as extreme as an extreme alpha can be, he was born like that, as in born with purple eyes and emitting pheromones.
Thank you for the clarification but I remember this interaction in the Polo match where this POS said that if Yeonwoo was marked, he will not react to his pheromones
Because it's not really affecting them, what I mean is an marked omega will be aware that the alpha is releasing pheromones, but they don't go into heat or something.
Josh is aware that Grayson is releasing pheromones, but not really affected by it, compare it how he reacts to Chase's pheromones. And alphas can't smell any other omega pheromones when marked by an omega.
But who knows, sometimes the author changes things. At the beginning it sounded like both parents needed to be extreme to have extreme offspring. Now it only guarantees 100% extreme offspring I think, even betas can have an extreme child if ones parent was one or so.
And with Grayson you don't know, he is a special case.^^ If any alpha could affect an marked omega it would be Grayson, I think, but he is most likely not allowed to do that. His father forbid him to commit any crime.:D
But Dane can knockout Grayson with his pheromones, so extreme omegas can be scary too.^^
I don't understand, how can Josh still be affected with Chase's brother's pheromones? He's marked right? They're in the same universe as KML so the marking thing rule also exist here.