A-Ko was originally designed as a female, but has chosen two distinct forms and personalities. One is a goth teenage girl who is overly excitable and bubbly. She is lightly flirtatious with just about anyone. The other is a teenage gay boy, completely infatuated with his friend and ship-mate Sirah Abrim and rather jealous of anyone else who gets his attentions. Sirah has not attempted to repair this malfunction, as A-Ko refuses to believe there is one, and it doesn't hurt Sirah to let him/her be happy. The male personality can be... Difficult to cope with at length.
Frequently the AI will get upset, though being upset doesn't last long. Moods are fleeting and come and go quickly without lasting impression on him/her in any case, unless something is serious. In any case, he/she will tend to throw holographic marshmallows at people when upset. The more upset he/she is, the larger the marshmallow.
A-Ko is designed to do a variety of general tasks, though Sirah treats him/her like he would any crew person, allowing ample down time. She is capable of managing all starship operations of any given vessel that Sirah is using and is capable of doing so for even a heavy cruiser type of ship such as Federation Galaxy Class ship without assistance, provided there are holographic projectors or some kind of robotic assistance for maintenance that cannot be done through software.
Flattery definitely works on this particular AI. In either form, she loves to be told how cute she/he is and how much her work is appreciated. She really is on the top end of brilliant, even though no one would guess it by her personality choices.
Sirah obtained A-Ko from a Ferengi during a trade deal at a significant discount. His favorite comment regarding this is "Never buy a discount AI from a Ferengi who is passing through the quadrant." As far as is known, there was no person who was the basis for A-Ko's personality, but if there was, they would likely be under psychological management. Not much history beyond that is known, even to A-Ko. There is a substantial probability that the Ferengi which sold the program to Sirah in the first place obtained it under less than reputable means. A-Ko has no memory before being brought online under the care of Sirah and was originally programmed to be his complete servant and property. Sirah managed to, with the help of some friends in Starfleet, remove those directives which appeared to be added after the AI personality was originally developed. This furthers the idea that the AI was obtained under less than reputable means and by someone without the proper skills.