Harp is a close friend to Bigby Wolf, who served as a soldier in World War II. It appears that Harp had knowledge of Bigby being a werewolf, though its uncertain if he knew he was a Fable. In Cinderella: From Fabletown With Love, he at some point also met Cinderella and he could have possibly fought alongside her during her spy missions with Bigby.
During World War II, Harp was sent to help Shawn Duffy and his friends on a special mission to discover a plan the German Nazi scientists were doing. Along the way, he enlisted the help of his friend Bigby Wolf. Though the soldiers never saw what or how he did it, Bigby often helped provided food and hiding places for the soldiers.
After a prolonged fight, Bigby managed to sneak into the castle where they were hiding. He discovered that they had Frankenstein's Monster and were apparently going to use him as a weapon. However, after Bigby fights and defeats the monster, the Nazis reveal their true plan. It was a ruse to lure him out and find what it was in his DNA that made him transform. Hopefully they could create other werewolves. But Harp came to Bigby's rescue and killed most of the Nazis, however he was mortally wounded. And he refused Bigby's help, insisting he get out.
Before the castle blew up, he asked one request from his friend. To tell all his "girlfriends" his last thoughts were of them.
Harp would reappear again in Fables: Werewolves of the Heartland. During Bigby's search of a new Fabletown position, after the sudden invasion by Mr. Dark. Before the Woodland Building was destroyed, he and King Cole had discovered Bluebeard had been making financial dealings with the Iowan town called Story City. In some ways, it appeared he owned the town. Bigby decided to venture to it as a possible new Fabletown. It appear secluded by forests. He'd soon discover werewolves lived in the town after stumbling upon them hunting a helpless mundy. He had no time for action as they soon tranquilized him. He awoke to a surprise, Harp alive as the last time they met.
He agreed to let Bigby out of his prison cell if he agreed to let him parole him. Bigby reluctantly agreed, to find answers. Harp had married with three slowly aging werewolf children Carl, Oda, and Alwin. His wife Sigi was also none other than the former Nazi doctor, Sieglinde Von Absensberg; something that shocked Bigby. During a visit he learns that in some way his blood had an affect on him and the doctor. Its suspect that when Bigby's blood had been split during their battle in World War II, it got into their systems and infected them.
They became werewolves and encountered one another. He and Dr. Abensberg fought for many days until they decided to stop. Harp felt guilty after innocent people had been killed during their battles. Eventually, they reluctantly worked together to survive in Germany. At some point, mostly due to Sigi's urging, they began to create their own group of werewolves. Though not in honorable ways, its not known why but at some point Harp went along with her methods. They began kidnapping people and forced them to become werewolves, one was an orphan girl. It was hinting that they killed her parents, thus making some of their members forced to rely on them.
At some point, Harp and Sigi married and fell in love. Sigi used her Nazi status to smuggle their members out of Germany and into South America. Eventually they made their way up to the U.S., its never been stated how Harp met Bluebeard or knew of his connection to Bigby. It can be assumed Bigby revealed his whole nature as a Fable to Harp during World War II. While Harp and Sigi felt proud of their community they had built, Bigby had a clear disdain for the town.
It was clear they had made a horrible mistake creating the community. He noted to Harp, he could tell that he had changed completely from the person he had known in the past. He noted to Harp that the town was obviously under a Draconian law and violations were punishable by death. And that they were willing to kill their own at an alarming regularity. During their walk, Bigby summed up what he saw for this town. The town was doomed with its repressive laws, not taking consideration of many alphas wanting to lead, and not taking into account for the now wild nature given to each town folk.
Harp was either to blind or to stubborn to see that his friend was right. Unknown to him, his own sons were planning to kill Bigby, Carl being the main ring leader along with his lover Diana. Carl had no sympathy or remorse knowing his own parents would be considered casualties. After Harp left Bigby, Alwin's posse attempted to kill him and Oda. They proved no match for him but he spared Alwin. But with a price, he made him promise to take his sister out of harms way, as he could tell Carl would come after him next.
As Bigby fought off against Carl's group, Harp and Sigi watched the outside chaos in worry. Sigi blamed him for not killing Bigby when he first entered town and demanded he kill him now with the silver bullet. But Harp couldn't bring himself to kill Bigby, remembering all the good he did in the war. Whether fear of Bigby, pure cowardice, or her Nazi training, Sigi committed suicide right in front of Harp. This left him in utter shock and he went for a walk during the chaos while his son attempted to kill Bigby.
Bigby finally put an end to Carl after he tried burning him inside the carousel building, willingly killing his own townspeople. It was the final straw Bigby could take seeing the a true monster that Harp and Sigi had raised. He killed off Carl and Diana along with the rest of the group, save one to teach them a lesson.
The morning after the chaos, Bigby appointed Alwin as the new pack leader. He decided to give them a form of freedom but with rules and one of which was to put a ban on all hunting humans as there was no honor in killing helpless prey. He decided to spare the town as they weren't Fables. But not Harp, to Bigby this whole mess was his fault because he had been a weak leader. He beheaded Harp to prevent more chaos from happening. Bigby left the city, hoping to never see it again.
Though Harp was finally dead, Bigby's connection with his family may not yet be over. As his daughter planed to leave Story City. As she saw Bigby leave she whispered "We're not over yet". Its not known if she meant by Story City, or if she'd continue to pursue Bigby.