IMO: Persephone is a program written by The Oracle and the Architect in unison, to investigate human emotions – and now keeps an eye on exiled programs.
What does she DO in M2? She helps the system get Neo to the Architect. She delivers the Keymaker. I think the Merovingian is far more dangerous than we’ve seen this far (his name btw, in case anyone wants to know is derived from a line of French kings from the 5th to 8th century, and a later order of the grail. The Merovingian Order of the Holy Grail).
If we look at her from a storytelling point of view, she is a n obstacle to get to the Keymaker. Just as Seraph is an obstacle to get to the Oracle (fighting), she is a problem that must be overcome to get to the Keymaker (emotions). It looks as if she tries to seduce Neo (and I still hope Trinity gets to shoot her in Revolutions 😄). But she makes sure that he gets to the Architect.
We seem to know the purpose of most of the programs running around. Attack-programs, help-service, hack-programs, viruses etc. We meet exiled programs who run around doing something they’re not supposed to.
The mother, we hear, was originally written to investigate aspects of the human psyche. That sounds like this entire over-ego, ego, subconscious desires etc. etc. etc. Correct me if I’m wrong, my Jung is fairly rusty. Maybe Persephone was written to SAMPLE human emotions.
Vis-a-vis… love.