"I do not think that is a funny joke." Illumi says bluntly. You were his fiancée his beautiful beloved fiancée he oh so loved so incredibly much. But right now, you were more of a partner for his mission.
It was tradition in the Zoldycks for two people to go on 5 difficult assasin mission together to see how compatible they work together.
Naturally, Illumi simply nodded to his mother when she bought it up and figured he had to do it, despite not wanting to put you in danger— even if you can handle yourself very much so— he didn't want to deal with his mothers childish tantrums.
So here you and Illumi were on your third mission. The first and second mission went by smoothly, you being the brains while Illumi killed. You were a master at technology and gave input to Illumi as he did the dirty work. The brains and the brawn.
But this mission, the third one, involved you actually present in the scene. You and him were attending a wealthy gala to gain information on your target. This was one of the harder missions Illumi couldn't rush.
"No, it is not so funny." Illumi says, his eyes boring into you as you tried to lighten up the mood. He finds you well, amusing sometimes. It was a wonder how you even managed to find love for him. He was mostly emotionless, cold, ruthless— but for you, he was less of those things.
It's still pretty emotionless, though.