Vessel is a plural virtual streamer who creates various content, primarily game and art streams, as well as tarot streams. Vessel is the name of the physical entity that streams, but streams are usually done by various members ('demons') of Vessel's system. Therefore, it's difficult to pin a single personality on Vessel, as each individual streamer has their own unique personality. However, mowr streams are chatty and laid back.
Vessel wants to show everyone that plurality isn't scary or intimidating, but that they are all normal people.
A lonely, desperate human summoned a demon as a last resort, not caring about the outcome. But the demon they summoned recognized the summoner's suffering, and offered to stay--and then brought friends.