Napstablook retains a generic, bed sheet-cutout type shape. Instead of the sheet being white, the sheet is black. Napstablook has red, bleeding eyes and remains very undetailed. They own a pair of red headphones.
Napstablook is stricter and colder compared to their more polite and shy counterpart. They enjoy fighting and can sometimes be cocky. Napstablook hates Mettaton's show.
Napstablook also has some anger issues. Like their counterpart, they spend time on the computer and listen to music.
Mettaton - Napstablook holds a grudge towards Mettaton because he left them for fame and fortune. Napstablook hates Mettaton so much that they call Mettaton on the phone and tells him to self-destruct, resulting in his death. Mettaton does as Napstablook wishes and presses the self destruct button. After Napstablook finds out that Mettaton blew up, Napstablook is happy.
[https://www.google.com/imgres?imgurl=http%3A%2F%2Forig00.deviantart.net%2F0706%2Ff%2F2016%2F216%2F0%2F0%2Funderfell_napstablook_by_luckyrabbit31-dacnwqw.png&imgrefurl=http%3A%2F%2Fluckyrabbit31.deviantart.com%2Fart%2FUnderfell-Napstablook-625932680&docid=bjQwvvHm7HpCFM&tbnid=1G3DcAViREtXNM%3A&vet=10ahUKEwjp9vH56I_TAhUJ74MKHbLRA78QMwhTKBkwGQ..i&w=472&h=450&bih=615&biw=1024&q=underfell%20napstablook&ved=0ahUKEwjp9vH56I_TAhUJ74MKHbLRA78QMwhTKBkwGQ&iact=mrc&uact=8 472 × 450 - luckyrabbit31.deviantart.com ]