Seth had never possessed a living body before, well except for his own of course. But ever since he had acquired the ability to transfer his soul through [Resonant Threads] he had always used it to transfer into his puppets, which always happened to be created from inanimate objects.
That was the description of his abilities after all, the ability to make inanimate objects come to life and obey him like puppets. But bodies and corpses were technically something he was able to do, and had controlled in the past.
It was just... when he found the true blessing of his powers, he stopped relying on corpses. It wasn't something he enjoyed doing in the first place. It was wrong, immoral and just downright gross.
Bodies rotted, they decomposed. If he really wanted then he could have breathed for them and kept their heart beating, like he was a living life support machine, to stop them from rotting but that, for some reason, felt even more wrong.