The Eleventh Doctor described the Entity as a mental parasite. It fed off will, ambition, creativity, which were usually tied to the desire to make trouble. Individuals the Entity fed on became docile and ready to accept almost any working and living conditions they were offered.
Feeding required direct contact and was more successful if the individual voluntarily invited the Entity into their minds. To achieve this, the Entity created an image of what the individual wanted and could not resist. However, the complexity of this image was limited. For instance, a complex concept from higher-dimensional physics was outside of the Entity's capabilities.
The absorbed parts of individuals' minds were digested slowly, making it possible to restore the individuals to their original state if the Entity was sufficiently destabilised. (COMIC: The Friendly Place)
SERVEYOUinc sent an expedition led by a chief scout to explore the possible uses for the Entity. It wanted to learn, instead it was subjected to an electrocution. Attempting to escape the pain, the brain of the entity, ARC, separated itself from the rest, which he called "mass". At the same time, the Entity sucked in the Talent Scout. His team towed the Entity to SERVEYOUinc City. (COMIC: Four Dimensions)
A portion of it was separated and sent to Rokhandi. It fed on life forms' creativity, will and desire to cause trouble, which were all interconnected. This was used by SERVEYOUinc to keep customers and employees of Rokhandi World happy and docile.
More than a decade after its capture, the Rokhandi portion of the Entity tried to feed on the Doctor's desires. When he wished a temporal concept he himself had taken eight years to master in Time Lord Academy, the Entity could not process this wish and got destabilised. The Doctor described this as the Entity vomiting. Most employees and customers were restored to their natural state and staged a revolt against Chief Security Officer of the theme park, August Hart. (COMIC: The Friendly Place)
But the thought of a time machine awoke the Talent Scout in SERVEYOUinc City, who emerged from the Entity and quickly took control of SERVEYOUinc and the Doctor. (COMIC: The Rise and Fall) They used the Entity to expand the TARDIS's matrix to the whole of the city, but the Entity was hurt by this process and required narratives, stories as food.
It took control of a Cyberman ship to create an army to defend itself. The ship crashed to Earth in Rome in 312. There the Entity continued using its ability to give people what they wanted to recruit more soldiers into its army. It also took control of John Jones. The Doctor managed to stop the Entity from taking control of the whole planet by getting it into contact with ARC, through himself. (COMIC: Conversion)
Having absorbed Jones, the Entity decided to run again, this time to the time before there was anything. The Doctor managed to contact it again through ARC and asked Jones to help pacify the Entity. Jones sang to it about love and caring. After that, the Entity fashioned itself into a saucer-shaped timeship and brought Jones back to the Doctor and Alice in Rome. Jones was now in a symbiotic contact with the Entity, playing the role of its spokesperson. ARC took the equivalent of the captain's seat in the Entity and they finally reunited. The Entity, ARC and Jones brought the Doctor and Alice to London around 2015, where the TARDIS ran away to. Soon after the Entity returned to being a free celestial body. The Doctor, Alice and Jones brought the Talent Scout and it was reabsorbed into the Entity. After this, the Entity let Jones go. (COMIC: The Comfort of the Good)