In many historicals dramas, the emperor bestows marriage to a couple. Sometimes it's seen as a good thing, sometimes as a bad thing, mostly it's an honor. I get that it's an order, so they can't say no, but what exactly does it entail? In a practical sense? Does the emperor pay for the wedding or something? Does he force the two families to form an alliance? Where's the difference to a normal marriage? And does it distinguish a family, if the emperor bestows a marriage on a couple? Even if it's a marriage that might not be seen as great, otherwise (thinking of "The Story of Ming Lan" here, where the emperor bestows marriage to a Marquis with the daughter of an unfavored concubine, which other's do not see as very advantageous)?

And I know in dramas it happens quite often, but did it happen often in reality, as well? Or did it happen differently in reality than in dramas?

I'm really curious about that, does anyone know a bit of the history behind that custom?