Arrow and Macduff are similar because both are caught up in circumstances they cannot control and wish they could avoid.
Arrow is a sharpshooter turned sniper in The Cellist of Sarajevo. She does not want to be part of the war, or to kill. She has to, to protect the cellist. He is a symbol of hope to the people of the village, and she must protect him.
…[A] man sitting in the street playing a cello will not be able to move quickly, and he will still be there to shoot for a few seconds later. So it would be best to eliminate the first person most likely to shoot you in return. (p. 88)
Arrow realizes that her role is a crucial one, even if it was not one she wanted. They are at war, and people are in danger.
Macduff is also peace-loving at heart. When he goes after Macbeth, he does so out of equal parts revenge and desire to eliminate the tyrant.
Hold fast the mortal sword, and like good men
Bestride our downfall'n birthdom. Each new morn(5)
New widows howl, new orphans cry, new sorrows
Strike heaven on the face, that it resounds
As if it felt with Scotland and yell'd out
Like syllable of dolor. (Act 3, Scene 3)
He does not want to fight, but he feels that Macbeth has given him no choice. In the end, he does take out Macbeth, and save the kingdom from the tyrant. Arrow (Alisa) is not as lucky. She is captured in the end, but retains her humanity.