Huh. I'm of the opinion that Jason doesn't swear. He can be very defiant and offensive and defiant without using that sort of words.
A character I can see swearing just fine? Bucky in Marvel, for example, who, I think maybe, has actually said the F word once or twice in panel. Kaine Parker too. But for whatever reason, I picture Jason just being really polite when choosing his words for swearing, most of the time at least.
Which means that most of the fanfics don't get the voice I picture for him in my head.