Board Thread:Episode Discussion/@comment-79.118.186.70-20180415020517/@comment-40230049-20191212233758

It could be that the writers may have intended on addressing the subject of Kelly's betrayal in detail. But if they did that, then Nick couldn't have a professional relationship with Eve. That whole backstory would get in the way of her providing him with intel. The other thing I think prevented it is that Nick would have to investigate Juliette's torture and indoctrination into the alter personality of Eve. There were enough storylines cluttering up season five, so I think in the best interest of the characters, the writers did what they usually do with storylines that have potential. In other words, they dropped it abruptly. Nick addressed it once to Eve, then promptly never brought it up again.

I rather wish the writers would have done as you suggested in season 6. In other words, have Nick actually take special care with Eve. Instead they left that to Adalind, with Diana thrown in to make Eve uncomfortable every now and then.