A Very Unwelcome Wedding Gift

Erich was the kind of man who absolutely would not let his plans fail. And with Lunaria, her hatred for Daelia outweighed her fear of Tia. After all, she had been the one to put down the AI menace which once ravaged the galaxy and brought forth the end of the Primordial Era. 

If she could do it once, then why couldn't she do it again? Of course, that was neglecting to mention that the sacrifices of the early Dark Elves had indeed been invaluable in that rogue AI's destruction. But Lunaria was far too proud to announce this. 

Regardless, Erich knew Lunaria would never in quite literally a million years agree to Erich's proposal. At least under normal circumstances. What was this one scenario where Erich could get Lunaria to agree to his request?