(Three ways I thought of Dark Side Logan going, couldn't pick just one!~)

1. (Numbness Logan) Warning- Not specifically unsympathetic sides but could be if wanted, more like what Logan thinks he has to do for the others to take him seriously 100%:

Logan gets fed up with the others treating him like he had no emotions so he decides to do something about it actually get rid of his emotions which adds onto his trait. Logan not only is Logic but he is now Numbness. He changed his complete appearance to be like a robot, making himself metal with robot features; his eyes big pure orange circles, his mouth never moving but lighting up when he talks, glasses gone but steampunk goggles on his head where he can put over his eyes, in his old shirt, his tie now replaced with a lab coat, and some of his metal was broken or cracked a little from his difficulty. He doesn't show any reactions whenever he is called upon and only speaking when he was spoken to.

2. (Insanity Logan) Warning- Unsympathetic Dark Sides:

Logan gets kidnapped by the dark sides after Janus had gained their trust and actually was using their trust so they could take Logan and leave the light sides defenseless without their Logic. So they force him to change and to become insanity. Remus changes his looks. Instead of his normal attire; he now wears a orange sweater with a black overcoat, black pants, his eyes black with tear like patterns down his cheeks, his glasses smashed but still on his face. He believes that the others let Remus and Janus take him since Janus lied to him that they didn't want him anymore and wanted nothing to do with any of them so he resents the others for allowing it.

3. (Anger Logan) Warning- Might seem like unsympathetic Light sides but could just be a grey area where they don't understand what they did wrong, ignorance kinda thing if you will:

Logan is angry at the others for pushing him aside and practically replacing him with Janus so he completely destroys his room and let's all of his anger out. Nobody can hear him besides Remus since he knows everybody's unwanted feelings. He finds Logan completely broken and decides to take him under his demented wing and helps Logan replace all that have left him. Remus completely changes his looks. Instead of a normal polo and tie; he now wore a ripped black t-shirt, a dark leather jacket that hung over my shoulders a bit, black jeans, and his glasses were now cracked, and his arms had lightening strike like patterns all over his skin.