While the rest of the world believes AI's are a clever Sci Fi plot they are very real in the town of Eureka. Taking all shapes and sizes and performing a variety of functions AI's are a part of every day life for the resident of Eureka.
Many Ai's introduced in the show have been portrayed has very naive and childlike and possess little or know understanding of things outside their field of duty. Because of this they can sometimes lack basic understanding of human concepts and inadvertently cause more harm than good. More advanced Ai's however can blend seamlessly in to society provided you do not know you are talking with an AI.
AI's can even develop mental problems just like a living person and these problems can be either benign or dangerous. The AI BRAD became psychotic when he developed the concept of offense being the best defence and as a result killed many test subjects he was simply supposed to interrogate. Nathan Stark even stated BRAD enjoyed killing because he viewed the interrogations has a game and he always liked winning. SARAH a benign AI suffers from severe abandonment issues in the first season which stem from the fact she was designed on top of numerous scrapped AI's. For much of the first season she is secretly terrified of being abandoned again leading to seemingly neurotic behavior around Jack Carter for leaving her out of the loop and other reasons. Her fear is revealed when Carter threatens to leave Eureka due to a bad few days and subsequently exacerbates the AI's fear to the point of holding Carter and several others hostage. Carter is eventually able to deduce the reason for SARAH's sudden violent behavior when he remembers how her predecessors were abandoned and along with the others is able to calm and reassure the AI that she wont be abandoned this time.