"Why should I patch things up with House Remus now?"
Eren asked while gently leading Dianna. Step-touch, Grapevine, Jazz-square, pivot turn, and Chasse were performed seamlessly by the couple one move after the other as they discussed.
No movement was wasted. No move was unpolished.
Dianna knew Eren would not do everything she asked because they were together. He needed assurance of tangible profits first before he could even think about patching things up with House Remus.
Of course, Dianna also knew that Eren wouldn't step out of his way to seek revenge at the cost of self-harm either. She just needed him to offer leverage in the deal.
"Eren, you should consider talking with House Remus because it can help you deal with House Slughorn. Because it can offer you precious resources at the right prices before they are released on the open market."