Responses
I also thought about emperor wanting to summon Sienna into Lylas body but...that would be so fucking twisted I think Sienna would just fucking killed him ....xd imagine being dead mother and then waking up in Your dead daughter's body, which father wants to fck u again...so he would have s€x with his own daughter, cause the body still contains his genetics, not only mothers.....that would honestly be too fucked up xddd
May contain Spoiler!!
Soo we all know that the emperor told the FL to protect the body (Lyla) and we know Sienna summoned the FL soul with magic. Now comes the twisted part (it was hinted at befor): I belive the emperor wants to summon Siennas soul into the body of Lyla. Lyla does resembel her mother a lot and i do believe the emperor became opsessed with Sienna as she told him she didn´t fall in love with him. And maybe he thinks he can set things "right" if he gets her back.
Sienna summoned the FL with the believe that she could protect Lyla from the future, but it seems to me that this set everything in motion and was proof for the emperor he could summon Sienna, even if she is dead. And he needs Lylas body and heck a lot of Magic (Siennas Magic) which ist possessed by Lyla (ergo FL).
Concluding this we can say: Emperor (and Empress) u piece of sh*ts, go rot somewhere and don´t come back ヾ(❀╹◡╹)ﾉ~