PLEASE HELP MEEE!!!!!! IMPORTANT!!!!

They are not brother and sister ,they were just raised as brother and sister. It has been revealed that kaname is the kuran ancestor, too but yuki stil calls kaname oniisama now she calls him kaname though. On a side note, it would not be wrong if kaname and yuki were brother and sister cause vampire laws and customs are different from human ones. The rules which apply to humans dont apply to vampires.

he is not her brother....he is the first ancestor of kuran family ...so it's perfect for them to be in love....

well siblings only mary to keep the bloodline going. to stay pure blooded. youve probably heard this a million times but it isnt all bad. because kaname insnt even related to yuuki if u get to chapter 52. well sort of but, she still loves zero anyway. its abit like days of our lives realy!

they are not brother and sister there just raise like that, in the manga it is reveled that kaname is actually yuki's ancestor,and he just taken the place of yuki's real brother which ironically has the same name as his hence (kaname kuran). it's because his real brother was sacrifice door kuran rido in order to revived the ancestor kaname cause rido wants to drink his ancestors blood for meer power but his plan backfired because it's obvious that he has beaten meer that he could chew. when he tried to drink his ancestors blood.