I am playing atm and I have just has something different happen and I wonder if anyone can tell my why/what happens in this bit?...I will put it in spoilers, though I doubt anyone would care tbh.
I am replaying atm, doing the main quest and I was doing the Thalmor Embassy quest for about the 4th time. Basically every time I have done it before, there has been 4-5 people in the party bit, where you have to cause a distraction...of the top of my head there has been me, Erikur, the Thalmor guys and Maven Blackbriar. Now on this playthrough whilst doing this mission I found that there were about 15 people there including the Jarls of Soliyude, Whiterun, Falkreath and Morthal. Also Proventus something, Vitoria Vicci and some other characters from other parts of the game.
This really took me by surprise as it has been different all the other times I have done it. Does it play differently based on some factors I am not aware of, or did I have a bug or something?
Yep, basically it depends on what quest lines you have done. For example the dark brotherhood will mean Maven is there I believe. Its basically the people you meet through those quest lines.