Known about the show, but long story short, they aged up all the kids on the show, some significantly. Hopefully u can fill in the blanks from there

On to who's regent? Good fucking question lol, it's one of the many reasons I hated ep 2 of this season, one of the things that just didn't make sense, in uncle Kevin lannisters dressing down of cersei (which otherwise was great) he says "ur just the Kings mother" so I guess, inexplicably, cersei, who was regent for tommens OLDER brother is suddenly just the queen mother for tommen who is king at a younger age than joff was

Like that doesn't make a lick of sense but oh well. I haven't the slightest clue who is regent, seems like they are saying it's no regent and tommen is ruling in his own right

Which leads back to the 1st question, why is cersei running the SC.