A) Fairy tail ending:
>Jack hugs Ashi and kisses her, willing to die at her hand. Ashi stabs her sword into Jack, with Jack falling to the ground, dead. Aku places the sword down and starts to celebrate. The moment, he turns around, Jack stands back up, picks up his sword, and jumps, cleaving Aku clear in half. His body lies, near death, asking how he's still alive. Ashi turns, and the black goo covering her face opens, revealing that Jack's kiss allowed her the strength to overcome Aku's control, and now she controls the power. She only pretended to stab Jack, and when he realized what was happening, he pretended to die from it. Ashi then holds out a hand, using her Aku powers to create a portal to the past, then forces her Aku goo off of her body with will power, and it rejoins with Aku's main body. Then, Jack finally finishes off Aku once and for all, and Ashi and Jack jump into the portal she made before it closes, sending her and Jack back to Jack's time. They both run in and encounter weakened Aku just as he sent past Jack into the future. They finish off past Aku in this weakened state, and due to time travel stuff, both Ashi and Jack aren't erased or anything. They live happily ever after.
B) Dark ending:
>Jack gives up, and kisses Ashi as he awaits his death. Instead, Ashi gains control of her body for a short time, and begins to fight Aku. Aku warns her, if he dies, she dies too. Ashi says that she is fine with that, and manages to knock the sword out of Aku's hand, and Jack catches it. Then, Ashi kisses Jack goodbye, and makes a portal, pushing Jack into it sending him back to the past. Aku tries to chase him, but its a stalemate between him and Ashi. Jack goes back and kills Aku after he sends Jack back to the past. The future gets erased so that the world where Aku ruled is gone and replaced.