His eyes analyzed you as you argued with Hidan, he huffed a bit and his eyes narrowed at your attention being on Hidan. You and deidara always argued over the littlest things..but even so, he couldn't help but grow...attached.

And seeing your attention on something else instead him, and another man nonetheless...aggravated him.. so he had to do something to gain your attention...and he'd do just anything to have your attention..