You know what, even I think that Narayani is good, and that she is a front for Krishna.
Think about this: Maybe he never did die, but got saved (Somehow..lets leave that to the 'creative' writers for now..). 😃 He decides to hang low and see who was trying to harm him and his family, and to what extent they will go to. By then, Janki gets sent to jail. At that time, Krishna conspires to send Narayani devi into the jail to help get Parvati out. Then on his instructions, Narayani devi/massi helps get Janki out, stage her death, change her identity and train her for 18years..all following Krishna's instructions.
(Remember massi saying that Krishna was the biggest Chaliya and he used to do everything to make the right things fall in place.... double meaning?? think about it.
..and I think that whenever massi gets scared and says janki should never know about this etc, I think its because Krishna doesnt want to be traced just yet...and massi needs to 'make sure Janki never finds out'. Janki's strength comes from the fact that her husband and son were killed so ruthlessly and her mission in life is to now teach the perpetrators a lesson. If she were to find out just yet that Krishna is alive, she would break down and become the same old Parvati that everyone including her daughter Shruti used to bulldoze over left and right.
I definitely dont think Narayani is even 1% negative. Each of her so called suspicious-looking acts can be explained if we think that her motivation to help Janki stems from someone else's motivation, someone whose identity needs to be kept a secret under ANY and EVERY circumstance!