I'm currently working on a world where there are people that live in data bases (basically a computer with no internet connection). They link to a human for life and and can record everything the human experiences (this can be shut off by mutual consent of the human and the database for a period of time), as well as record all events that happen in the same room as them (kinda a sonar/radar effect). They also have the ability to project an avatar and speak (these are independent e.g. they can speak without the avatar). The size is variable, but is always easily transportable by the human.
Here is where it get fun. They are unique individuals, much like humans. I wanted to avoid the "handwavium" of magic, but if it makes a difference, they are AI's built by magic to help casters recall spells in specific, but they also act as a perfect journal for that mage. This allows them to be personalized to whoever they bond with. But, a being with perfect memory and a want to help their human has a large chance of having personality quirks that are similar between individuals. Unfortunately, I'm not a psychologist so I have no clue (and couldn't even begin to guess) what this would do to a human-like personality.
What manner of personality quirks would be likely to develop in a human that is a database [for storage and retrieval of data](and so has perfect memory)?