It starts when he goes off to school, when the Regent and his family return to their ancestral home and leave the Residence, when it's clear that Lord Vorkosigan doesn't need to be near the Emperor in order to act as the Emperor. It starts when Gregor becomes, by his own law, another student, another prospective cadet for his own service. And nothing happens. He receives political and security briefings that are getting progressively more complex and detailed the older he gets, and nothing happens.
The Imperium continues ticking even without the child Emperor as a figurehead in the Residence. With the child Emperor at school with other children. With the child Emperor out of the way.
Gregor wonders if it's possible that his grandfather chose too well. That his choice of regent was too smart, too savvy. His grandfather gave him a military hero, a political animal, a relative. His grandfather gave him the best regent the government, the military, the people would accept. His grandfather gave him a regent capable of being Emperor. A regent with a claim on being Emperor.
And then his grandfather died and left it to Gregor to sort out, for Gregor live with, for Gregor to struggle beneath.
He will never be Aral Vorkosigan. He would never be permitted to try. He won't be allowed real risk. He won't be allowed to conquer planets and put down mutinies. He won't be allowed to choose his bride from among the galaxy. He won't be allowed to bring her home and make her his Empress. He won't be allowed to have a deformed heir. He won't be allowed to have only one. He won't be allowed any risk to himself, or his Empire, or the Vorbarra Imperial line.
They may as well lock him up in an ImpSec prison until he's of age and then in the Residence until he's fathered six or seven children. They may as well lock him up and let Aral Vorkosigan rule in his stead.
And Gregor can't even really hate him for it, because it's not like his regent is doing a poor job. It's the opposite.
Aral Vorkosigan is better at being the Emperor than the Emperor is. His grandfather gave him a great gift: the perfect regent, a man who can hold power for sixteen years, a man who can keep the Imperium in the palm of his hand.
If he can hold it for sixteen years, what's to stop him from holding it for sixteen more? What's to stop him from never giving it up? Honor, of course, Gregor thinks, and oaths, but Piotr Vorkosigan overthrew an Emperor and Aral Vorkosigan took first cut out of an Emperor and Aral Vorkosigan was there when Gregor's father died. Aral Vorkosigan survived when Yuri didn't. Aral Vorkosigan survived when Serg didn't.
Ezar Vorbarra gave his grandson a regicide as his regent, and the worst part is, Gregor thinks glumly, staring at his briefings, was that he was right.