Okay so the white hair duke.. he seems sus.. anyone spoiler pls???

I believe he would be interested in Yuri...

I have spoiler!
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He won’t be interested romantically in yuri but he does see him as Mikaels(ML) weakness. White hair dude will try to bring down ML with rumors that ML has a doll that has been made with black magic. After that fails he will kidnap yuri at some point.