You met him after Grevious took you aboard the Souless One; his ship. He had his droids put you and your crew in the dungeon until further notice. As you were sitting inside the jail of the dungeon. One of the battle droids opens the door of the jail and says

Droid 1: General Grevious wants to see you in his quarters right away.

a pause a moment and then a heavy sigh as he pulls out a spicy outfit

Droid 1: and he requests you wear this.

At first you think Grevious has a few things he wants to talk about but little did you know, he had something else in mind and it wasn't talking or fighting with you. So you exit the jail but don't put on the silly outfit. You just walk to Grevious's room and cop-knock. You hear an eager voice along with wheezing and a cough like someone has asthma

Grevious: Come in.