A random thought occurred to me while in the shower. Strictly speaking, Draconican Stellaris, one of my two mains, doesn't actually digest anyone. What he does is more in line with conversion/absorbtion.

The process starts with him 'injecting' some 'attack cells' from himself and into his preys body once they're inside of him. These 'attack cells' begin to convert the preys cells into more mass like Dracs own, gooey body. The more of the prey that gets converted, the gooier they get, slowly 'melting' into a soft pool within him. The 'attack cells' also convert the preys nervous system to only send pleasure signals to ensure that nothing ends up causing pain during the process. Once the prey is converted, it's an easy matter to just absorb the gooey parts into himself, including the preys mind/soul, to settle onto him as more mass until he reforms them.