I wonder, after being trapped in a fusion with Lapis for so long, if Jasper will have some affection toward Steven.
In the beginning I assume they just yelled at each other the whole time but after being in eachother's heads for such a long time maybe Jasper gets curious about why Lapis likes him so much.

If Jasper ever unfuses, I think both of them will have some personality traits of the other. Fusing for so long has to have some mental effect, just like how Ruby and Sapphire consider themselves 'we' even when unfused.

Maybe Jasper likes Steven more and understands Earthlings, and Lapis becomes more belligerent?