~Can she drink blood from your character? There's actually a blood bank run by Martha Jones at the Clinic (which Anders helps manage, the Clinic, not the blood bank,) so if she mentions a need he can direct her there. That being said, she can try, but he'd try to fight back and that might make an interesting bit of conflict.
~Can she transform into your character after drinking their blood? If we plot this out, sure.
~Can Diva give your character her blood? He won't take it.
~Is there anything that you want me to avoid talking about? Nope!