Marvus is a popular highblood singer with a cult-like following; his mere appearance at the music festival drives the crowd absolutely wild, which is also the reason why he has numerous bodyguards with him to keep him safe from harm. Just about everyone applauds his creativity and ingenuity when it comes to music and dancing, the player also noting that his lyrics aren't racist in the slightest. While Marvus is certainly happy with his fame in the creative industry, he off-handedly mentions that being perpetually pestered to pail with teenagers frays the nerves somewhat (that's why he isn't too upset with all his fans dying at the end of his shows; it's a normal occurence). Even so, performing for his adoring fans is something he clearly lives for, and wouldn't want to disappoint his loyal fanbase in any capacity. When the stage equipment goes haywire and falls apart, Marvus becomes momentarily despondent as his show is ruined for the night. 

While he is a well-known highblood performer, he doesn't take any pleasure in abusing his position on the hemospectrum. When the crowd demands that he publicly kill the player for show, he spares the player's life and instructs them to play dead so that the crowd doesn't notice what's actually going on. Marvus reveals that he saved the player's life because they felt bad for them; he's aware of Zebruh's less-than desirable personality and openly criticizes the indigoblood for constantly trying to worm his way up the social ladder. The purpleblood is also aware of the subtle oppression in regards of his caste; the seadwellers enforce rules and cultural precedents on the purplebloods in order to ensure their status as the superior caste. Despite not explicitly calling for rebellion, Marvus remarks that shaking up the system would certainly make things interesting. To top things off, Marvus goes out of his way to care for the player's well-being at every turn: saving them from crowd violence, consoling the player, feeding them food, shielding them from an explosion, and taking them to the one safe place he knows to try and escape impending doom.

Apart from that, Marvus is strangely aware of the time shenanigans and knows a lot in regards to reality and all the details that do or do not contribute to it. When the player uses terms that normally don't make much sense in context (eg: non-canonical decision), he's able to grasp their real meaning in mere seconds and add on to the discussion taking place. Marvus firmly believes that a person's fate is in their hands and not the other way round, stating that every decision made (irrespective of its actual significance) contributes to the overall essence of existence itself. Judging from the brief lecture he gives the player, he appears to be incredibly well-versed with the concept of reality and irreality.

Marvus is shown to speak in a very casual and easy-going manner; his laid-back demeanor doesn't change in the slightest even when things aren't going alright. This is best illustrated when he's injured after protecting the player from a sudden explosion: he still maintains an air of detached calm despite being in clear pain and tries his best to soothe the player about their existence in the universe. 

I'd imagine him having a thick southern accent.