It's a scene that never would have happened in the comics -- it was "too emotional," said Mignola -- but it worked for the movie.
"Guillermo del Toro wanted a drunk singing scene," Mignola said. "I just went, 'You're the boss. Whatever you think is going to work.' I'm shy about those Hellboy-Liz Sherman moments, but he knows how to pull those things off."
But if it was just intended to be your run-of-the-mill drunk singing scene, why Barry Manilow?
"Del Toro was adamant that it be that song," Mignola said. "I wasn't sure, and I was racking my brain, but I couldn't think of another song to suit that moment. So much of the movie is personal to del Toro, and he was married to that song. It says more about del Toro than it does about the characters!"
Breaking out into song wasn't the only distinction between the Hellboy of the comic book and Hellboy of the movie.
"Both versions can work," Mignola said, "but a lot of 'Hellboy II' is del Toro taking ownership of these characters and having them do things I would never have them do."
The memorable troll market scene from the film stands as an example of del Toro's influence, according to Mignola.
"I wanted something small and spooky," Mignola said. "Like he walks in there, the creatures scurry up the street, he's like a gunslinger walking down the empty street, with lanterns creaking back and forth, and one of the characters, a hooden figure with an iron key starts saying in another language, 'Remember, you are the beast of the Apocalypse.' Very German expressionist. But I use four colors, and del Toro uses the big box of colors."
Some of the things del Toro inserted into the "Hellboy" movies were leftovers, and others were just personal preferences, like the use of subways, arches, or the color amber.
"The whole scene in the first movie where Hellboy follows Agent Meyers and Liz Sherman like they're on a date?" Mignola said. "I'm 99-percent sure that was a scene written for a different movie."
Mignola said it's better to let del Toro put those personal things in there, because "he's a filmmaker who has a catalogue of things he wants to do." In being able to do them, explained Mignola, it helps keep the filmmaker passionate and, hopefully, coming back for more.
So what happens if del Toro wants Hellboy to sing again? How would Mignola respond?
According to Mignola, his response would be: "Dude, do whatever you want."
What did you think about Hellboy breaking into song in "Hellboy II: The Golden Army?" Was it out of character, a new side to the hero or a welcome bit of character development?