Toffee is a lich.
a lich is a powerful mortal who fractures their soul and places it into an object of importance to them turning it into a phylactery. The easiest way to understand is to think of voldemort. Now just replace the word horcrux with pylactery and boom, voldy is a lich. Now back to toffee. Even after he died he was still present and managed to take over ludo. Now, what’s his phylactery? an object of importance which harbors a fraction of his soul. well, were have we seen evidence of his presence in a place it shouldn’t be. well…

his finger inside the wand. A fraction of his soul in an object of importance. and what is the conduit throguh which he corrupts ludo?

the other half of the wand. and it was established that the two halves of the want are linked.
Now, here’s the question of the century. Who is Toffee? well, he has connections with the royal family, the wand, knew glosserick more than most enemies do and gained a massive power boost from eclipsas chapter. well, eclipsa is the queen who wed a monster.
so what if toffee is the child of eclipsa and the monster, making him the rightful king of mewnie and heir to the wand.
TL:DR
Toffee is a lich and the spawn from the union of eclipsa and the monster