MacDuff was a creation by the Adversary, and was seen often flying around his cottage. At some point, Frau Totenkinder used a spell and was able to use MacDuff's eyes to spy on the Adversary. After he was taken by Boy Blue and forced to "resign" as the Emperor, it left MacDuff all alone. He wandered through the general areas Geppetto use to go, along the way he spotted Jack Frost in a fight and came to his aide. When Jack asked his name, he said that Geppetto referred to him as "Owl" and feared he wouldn't see his maker again. Jack felt gratitude towards MacDuff's assistance and offered to do a deed to reward him. MacDuff offered to doing some wood repairs on him. However, Jack wasn't a trained woodscraft like Geppetto. But MacDuff offered to lead him and told him of a remote woodshop for him to go to. There Jack, quotes from MacBeth "Lead on MacDuff". When the owl curiously asked who MacDuff was, Jack offered that to be his name.
After tending to MacDuff, the two began a friendship and a partnership. Young Jack not sure what to do, since his mother was under Briar Rose's sleep spell and Jack Horner was no father to him. He decided to be a hero for hire and MacDuff offered to be an aide to his new friend in that business. Helping him look for any deed, no matter how small or ordinary (such as helping with crops or retrieving a lost goat to a farmer). Eventually Jack would get his big chance as a hero when a young girl Elsa Fen came and asked for their help. Creatures called Nightwalkers had been attacking her home and needed a hero for help. However, by the time they reached her father's hold-fast, the entire place was deserted.
No sooner had they got there but were attacked and taken captive by the Nightwalkers, however much to their surprise the creatures had kidnapped the people in order to find Jack. For they needed him for a heroic deed. According to Wruk Buk Tuk, a sorcerer had been using his magic to control them and anyone who got too close was put under his spell and attacked the other. Jack agreed, on the condition he and MacDuff would work out a binding peace treaty between his people and the humans. After a very long battle, Jack would defeat the sorcerer and there was peace, thanks to MacDuff's help. The two eventually crept away from the kingdom, because Jack didn't wish to marry Elsa, respectively.
Jack would later employ himself under the King of Landfall's services under the king's claim that Empyrean had been stealing gold and kidnapping virgin maidens for his own personal pleasure. MacDuff was not too fond of this adventure, due to the company Jack began to keep with Deirdre a witch who offered to help him. However, things weren't as they appeared as it was eventually discovered that both the king and Deirdre lied about him. Deirdre had used him for a domestic dispute against her former lover and the king had been using Empyrean's name as a ruse to get away with selling the maidens into prostitution and tried convincing Jack into being a co-conspirator.
He and Jack would go on through more years to have many more adventures. And Jack eventually gave him a few modern touches such as lasers in his eyes to help him in battle. In the End story arc, Jack decides to take one last final battle before retiring and decided to get rid of a dangerous dragon. Not knowing it was his own, semisane father Jack Horner who had shifted into a dragon from his own greed. Eventually MacDuff dies, trying to protect his beloved friend. Telling his friend that he loved him.