Okay but imagine instead of generic Darkness enemies, when you go to rescue Walter, the Crawler sends a shadow!Logan to fight you, and its basically an impression of your brother on the worst day of his life, fighting to survive as his men all die around him. Maybe there are minion shadows that, as you kill them, has 'Logan' yelling out the names of the men who died like you're the Darkness killing them in front of him and it makes him fight harder all the while he's insisting that he will get home, he has to get back to his sibling and that it won't take them from him.
And then you kill the shadow, and as it dies it suddenly recognises you as his little brother/sister and it dies wondering why you'd do this. And suddenly HOBW goes from being so certain that they're going to fight Logan and take him down and maybe even kill him, to being so deeply shaken to have killed even just a shadow of their brother, now realising that he fought and clawed his way back from hell for their sake.
Like damn, that'd have been a way to include a Logan boss fight even if the real Logan would choose not to fight his sibling, and it'd really force HOBW to take on a whole new perspective wrt their brother.
