The two times I have done that marriage it didn't work out as well as I would have liked.
Playing as Sicily I set up the marriage and I thought I was just way too smart, as I would control the majority of the peninsula... At first it was pretty cool and she helped me take Tunis (step one in any Sicilian conqueror's play book), but than as so many people above me said she decided hey I am going to go rebel against he HRE, and I was like sure I will help you. At first we were actually kicking ass, we got all the way up to Lombardy, and than through the mountains came the first of several 10k doomstacks. Blew my whole army, plus a bunch of cash of mercs and lost.
The second time around I was the Duke of Providence (ruler designer), she quickly helped me dispatch Genoa, but once again rebelled against the HRE. This time I didn't bother to even try to help her (nor did she request it). She did have a few powerful Dukes with her though and I managed to pull off an assassination of the Kaiser, however she still lost and was imprisoned (where she died), and our only child died before her so NOTHING for me.
Playing as Sicily I set up the marriage and I thought I was just way too smart, as I would control the majority of the peninsula... At first it was pretty cool and she helped me take Tunis (step one in any Sicilian conqueror's play book), but than as so many people above me said she decided hey I am going to go rebel against he HRE, and I was like sure I will help you. At first we were actually kicking ass, we got all the way up to Lombardy, and than through the mountains came the first of several 10k doomstacks. Blew my whole army, plus a bunch of cash of mercs and lost.
The second time around I was the Duke of Providence (ruler designer), she quickly helped me dispatch Genoa, but once again rebelled against the HRE. This time I didn't bother to even try to help her (nor did she request it). She did have a few powerful Dukes with her though and I managed to pull off an assassination of the Kaiser, however she still lost and was imprisoned (where she died), and our only child died before her so NOTHING for me.