He guessed it was from either tolerance or amusement that Ari kept indulging his antics and humor. It was probably not exactly indulgence since her demeanor and attitude wasn't exactly the most pleasant when he let out a real groaner of a pun. Still, she did not violently react or fatally harm him, so there must have been something there that intrigued her or at least found interesting enough to keep him around.
As a quasi-friend of Taylor now and the daughter of the Arbiter, a person who had impacted their family in a drastic way, her mere existence fascinated Steven. She was like a mystery he didn't know existed since it wasn't until recent years he found out she was even a thing. So, to have a gap in his knowledge of Zabökar history was an affront to his sensibilities. He needed to get to know this enigma of a person that was Ari.
To say there was resistance to this notion was an understatement. Still, he persevered despite being internally terrified of her presence and what she could do on a whim should he piss her off in just the wrong way. Despite everything though, she still allowed him to question her, joke with her, prod her for information and more. It felt like a love/hate relationship, but one he was willing to pursue because of reasons - not the least of which was... he kinda found her horribly attractive and she didn't shy away like many others from his natural musky scent.