Look… watching Orochimaru 24/7 changes a man … He needs something to get him through the day ( he would look cool that’s the real reason)
If anyone, I think Iruka because I can’t quite picture shinobi who are regularly in the field choosing to give themselves permanent identifying marks. (We’ll ignore that they identified ANBU with tattoos and distinctive clothing…)
In a Modern AU setting, though, I feel like it might be Asuma—as an act of rebellion against his father.
I love how everyone has a different take! For me, Anko came to mind first so I went with it (Imagine a snake from the hip, twisting up and around her torso!!! although I doooo like the idea of any AU that puts nice big tattoos on any of Iruka and Kakashi.