Sollux is seen as introverted, as well as having a bipolar disorder. In one instance, before he could be given a name, he sent the player away just to change his mind after the scenes switched. He's self-deprecating, often beating himself up about little things, such as how he thinks he isn't a good enough hacker when it's very clear he is. Due to his zodiac sign of Gemini, he has a liking towards bifurcation and duality, and often splits things into red or blue.

Sollux types S's with 2's and always doubles ii's. When he becomes blind later on into the story, his o's are 0's. By the way, Sollux has a lisp!