Comment by simo7

Not only they were cousins, in their private correspondence right before the outbreak of WWI they were addressing each other as Willy and Nicky[0]. By the way they fought against each other.

0: https://en.wikipedia.org/wiki/Willy%E2%80%93Nicky_correspond...

edit: I meant the correspondence between the third cousin, Wilhelm II, and Tsar Nicholas.