satella became the witch of envy after she absorbed conflicting powers.
satella and the witch of envy are seperate beings.
she can absorb other witches and beings.
she has control of the Authority of Sloth
she loves subaruu.
... My crazy theory....
what if for some reason, emelia ended up absorbing subaruu in the future? the witch of envy can clearly go back in time as she sends subaruu back all the time, she has control over the Authority of Sloth , shadow magic, and from what it seems like, she can use E・M・M and freeze his movements to choke his heart.... echidna meantuned being afraid of satella so she avoids getting in his way, yet emelia goes unchecked. oh... also... E・M・M is a type of space time magic, and did i mention satella can aborb powers? if subaruu went back in time with emelia and they became different people that would be hard to patch emelia going nuts, but if she absorbed his powers including the bad.
she refuses to let him die, but also "avoids" him... what if she absorbed him and his power, by accident, lost control and get sent back in time?
wakes up, with new incompitble powers that birth a split personality that is in emence pain and that dark personality lashes out?