Before you can see the Emperor, you need to complete the quests of Kaja, Loam, Hethrir, Thrawn and Veers, in that order.

Congratulations, you've made it to an audience with the Emperor. The Emperor is accessable from the elevator between the two royal guards in the main room. (like you haven't already been up there soon as Kaja let you in the building). He is impressive, kneel before him like Vader and utter "What is thy bidding, my master?" Its neat.

Emphasis again on the "capture" part. Let him engage you, then run around with him in very close proximity until he breaks contact. At that point, you will turn around and engage him in conversation as if he didn't just chase you 150m or more trying to kill you.

Thug Ringleader had 1400 HAM. No guards and wasn't agro. Funny thing was the meeting was at the top of the hill, but there was no visable sign of him though he appeared on both radar and you could tab to him.

Eventually discovered that he was actually under the ground some 3m, had to use tilde key as couldn't click to select him. Talked fine and he actually followed, he just popped out of nowhere.