The German actress initially had trouble understanding the different accents of her co-stars on set and admits she "didn't understand anything" before her language skills improved.
Kekilli originally had her scripts translated into German, but her grasp of English increased by the second series - much to the disappointment of actor Peter Dinklage.
She tells The Hollywood Reporter, "I had to get used to it. Because it was my first time acting in English, everyone on set was difficult to understand. It was a mix of Scottish, Irish, British and American English.
"To understand a Scottish accent or an Irish accent was so hard. I didn't understand anything. In the first season, they translated lines to German for me. In the second season, Peter said 'oh your English is getting better, so now I can't make any jokes in front of you.'"