Consider this: the tattoo is on Niki’s shoulder. When her normal personality is dominant, does she wear clothes with bare shoulders?
I’m pretty sure we’ve seen Niki bare-shouldered without a tattoo.
Did everyone completely ignore my point about the tattoo business being right up there with the eclipse in significance?
I’m not, but I’m just writing the whole thing off as being an unfortunate result of writing a show that is too complicated with too many characters and trying to tie all the varied subplots together into nice one-hour chunks with cliffhanger endings. There may have been an explanation written or even filmed that got cut for time. The actress playing Niki is hot, but her character is among the least interesting in a show with plenty of other stuff to look at.
I think the tattoo-thing is just a device to clearly show who the character is, no more, no less.
That way you can see immediately if the character is being Niki or Jessica.
There is no need for intricate plots for something that is basically a device to tell the story without needing to actually say anything.