Metamorph is able to fuse his vial inside of a living host (that must be made of flesh, making Omnias inaccessible), which allows him to share his existence with them, including his immortality, feelings and pain. When inside his vial, he can still see, feel and sense everything that his host is doing. Metamorph can also choose to manifest outside of his vial separate of his host or overtop them, though the latter is often only used as a defensive method. His vial coexists with the host's original heart and can be found on the opposite side of their chest. Metamorph's vial can be forcibly removed from its candidate, but the results are often fatal. Metamorph's secondary ability allows him to feast on magic in order to make himself physically stronger or to rejuvenate injuries. Since magic is potent in itself, Metamorph tends to avoid feasting from direct sources (the user) and instead resorts to feeding off of their emanated magic (spells/powers). Other indirect sources, such as most enchanted items that have been fused with magic, are also vulnerable to Metamorph's appetite. The inside of his vial seems to be a fleshy womb-like chamber filled with a breathable fluid. Small particles float around and the walls appear as translucent, veiny membranes that simulate the outdoor lighting experienced by his host.

When Metamorph enters his vial, he often curls up into himself and a mass of fleshy appendages descend to attach to the ends of his tentacles, effectively "connecting" him to his host so that he may directly experience their consciousness. If he doesn't do this, then he's probably in a state of complete inactivity due to a serious injury that he has to recover from or because he hates you. Metamorph's vial contains no Next door as he had already eaten it centuries ago.

Metamorph communicates to others using his loud and invasive telepathy. Metamorph has a high sense of self-preservation and survival. He doesn't like experiencing strong emotions since he finds them blinding or misleading, and therefore tends to force a state of neutrality or indifference onto his host.