I like it I vote halo. I honestly haven't read much mass affect and while it would be interesting to see either I do hope that lydia keeps her memories even if she goes through reincarnation also amnesia would also play a role huh.. short term amnesia so that extended beggining may be kept. Might I suggest warhammer and starting in a way that smoothly transitions from one era to another through time and that time is lighter in this setting. Another is starcraft. Altho I really dunno how you could make a sc2 fanfic xD Like cosmic power could be used but that would either mean lydia has been doing nothing up until late into the sc2 universe as only perfected hybrids something introduced later can challenge cosmic beings altho I dunno how psionic power can be compared to cosmic energy. However they gotta compare alot or else Kerrigan would not of been able to ascend. Also on Kerrigans passive you have on the epilogue is called 'cosmic fury' meaning she/Kerrigan had ascended to a cosmic level