So I could never picture Agent Stone as the cold, ruthless FBI / CIA type.
My headcanon is that before he began working for Robotnik, Stone was a barista. Like a really really good one, the kind you see making those super creative latte art patterns on instagram. Aban was just a laidback guy who enjoyed a chill, low stress lifestyle and so even though he's really intelligent with a bachelor in engineering (minoring in mathematics) and the potential to land a really successful lucrative career in any field of his choosing, Stone decided on a simple craft instead, one which he has perfected and takes a lot of pride in.
Robotnik personally poached him from his job at some small specialty coffee shop (not Starbucks, Robotnik wouldn't be caught dead in a Starbucks) because despite his impressive genius and undoubted ability to design and build a coffee machine that would steam perfect lattes every time, Ivo had better things to do with his time and it was simply more efficient to have someone else make it for him. So he's on the road in his [self driving.. utility.... van/truck/thing?] and goes in to this local coffee joint where he meets Stone, and after making some snide offhand remarks regarding Stone's lack of talent and belittling his intelligence, he is unexpectedly surprised when he receives the best damn latte of his life. It's the closest he's ever been in his life to being wrong (obviously NOT wrong though, he's never wrong; perhaps just not entirely 100% accurately correct) and this shocking revelation piques his interest in Stone, so he comes back the next week, and the next, until eventually he's a regular coming in daily (typically twice a day - first at 7:00 in the morning, then again in the late afternoon at 16:00, like clockwork - but on sleep deprived days it’s not unusual for him to stop in as many as seven times).
Through this working relationship Robotnik starts learning more about Stone, like his first name is Aban and how he actually isn't totally stupid and has a degree and reads physics textbooks for fun on the weekends and has an annoyingly beautiful megawatt smile that he shouldn't really be thinking about ... meanwhile Stone is getting him to open up and actually make small talk (mostly about himself), and Aban is thrilled every time he receives one of those classic compliments-that-aren't-really-compliments-but-are-compliments-by-Ivo's-standards like "this isn't totally disgusting" or "I suppose you are the least brainless person in this room ... aside from me" and unlike his coworkers who only see an egotistical arrogant bastard Stone is genuinely awestruck by his brilliance and once he finds out what Robotnik does for work, because he's such a people pleaser (*cough* and so hopelessly infatuated) Stone goes home and researches robotics so that he can keep up with Ivo's conversation and the next time he comes in Ivo is delighted and Aban is proud just to make Nik smile.
