Prince - Hung up on his self-righteousness, and pity.
Yulan - Think he is at fault for Vio's tragic end and doing this more to redeem himself from that error than for Vio's sake. Plus, the way he is infatuated with Vio seems similar to how old Vio is infatuated with the Prince. The fact he is in a similar family condition as Vio implies that he too is starved for affection, only he seeks it from Vio.
The best character is Vio herself. Lots of development. Old Vio is starved for love and seeks it heavily from others. "If it's the Prince, then I can get the love I yearned for". The newly reincarnated Vio does a complete 180 and thinks herself as not deserving any happiness. "I am the unwanted person anyway, might as well make myself disappear".