Answer:
BRAINLY OK SORRY FOR CAPS
The author's use of these characters' hallucinations creates tension in the play because the guilt that they have from killing the king earlier in the book. The blood is from the imaginary daggers that Macbeth sees but are not there in front of him.
That is 100% your personal opinion but I believe that it is everyone's personal choice wether or not they would like to serve. I believe this is a matter of decision and it should not me compulsory towards any gender