Lucifer is a character in the game Lucius. He is the father of the main character, a six year old boy by the name of Lucius. Lucifer wears a suit, and has a slight red tint to his skin. Lucifer is rumored to be the Devil, which explains why the house is on fire when he visits Lucius.
When you hold up a light source (fire), to Lucifer, you can see that his shadow has devil horns and devilish claws. This can be seen in the episode when PewDiePie learns the combustion skill.