BLUE TONGUE SKINKS

Hi! My skink, Toaster Oven, has a black line by his eyes similar to Easterns, but it’s very faint & I only noticed it because he’s about to shed. Is that normal for Northerns? Or could he actually be something else? I’ll attach a picture just in case.

Yes, that is normal for a Northern.
An Eastern's would be jet black.

I don't even see a black temporal streak. And an Eastern would have set you back the rent, if you could find someone to sell you one. Not even remotely similar, except for the queensland type which is virtually impossible to get over here.