He killed those boys out of frustration whenever they turned out not to be Anubis, whom Seth was desperately looking for since he had ran away. Anubis had ran away on him in anger and had been missing for quite a while (Anubis had actually gone to Duat and met up with Osiris during that time), so Seth was desperate to find him, morever because the missing Anubis was still "human" and that put him in danger along with making Seth unable to sense him out in order to locate him... The only way he could find him was by checking boys one by one, to see if any of them was him, that's why he asked the humans to bring him boys that fit Anubis' description: so he could check them one by one and see if any of them turned out to be Anubis. Each time they turned out not to be Anubis, Seth killed them out of frustration (Horus was only spared because Seth had already gotten high and drunk up to his eyebrows, and thus mistook him for Anubis).
Man JayJay coming clutch with these explanations (づ￣ ³￣)づ
why would seth leave & kill a bunch of lil boys?? also i may have forgotten but is there a reason why seth was so abusive towards anubis even though he actually loved him?