The fault, dear Brutus, is not in our Tsars, but in ourselves

*Note to be fair this situation came up in a ASB&M thread of mine but separate from that I thought it interesting enough to Ask in this forum

The P.O.D., what happens if Napoleon is able to win Big at Bautzen. An Austerlitz level victory at which he captures Czar Alexander.

So the question is what happens in Imperial Russia? Do they barter for his return? Do they move on and so begins the reign of Czar Constantin?

Candidates for Czarina (Maybe Britain offers Princess Charlotte to get Russia to form a 7th Coalition?)

He gave up all rights to the throne to marry his second wife but in 1813 that hasn't happened yet. I do not think Constantin's first wife, Princess Juliane, would return to him even if he was the Ruler of all Europe

Does Nicholas still end up Czar somehow?

and then of course there is what happens to Alexander (Not Czar, becomes happy?)

The 6th coalition is beheaded. Alexander was its soul and its main support in terms of military power.

Napoleon will keep control of the german confederacy and come to terms with Austria.

Whoever becomes tsar, he will have a different policy from Alexander's because he needs to secure his throne. Russia was more exhausted than France at the time. You can even expect an uprising in Poland on the russian rears.

What are your thoughts on Czar Constantin?