Dive into your creative stream
So I will preface this by saying that I am not an Iris hater but she never sat right with me after Bridge to the Turnabout. I'm a biased Narumitsu shipper but I do entertain other ships (helllllloooooo Langworth) but I couldn't get behind Feenris for a few reasons.
She's a victim, yes, but she's complicit as an accessory to crimes. We last see her serving time for covering up the murder of Misty Fey but this is just the one that caught up with her. There's been at least two times she was at least privy to Dahlia's crimes (the fake kidnapping plot, Valerie's murder, Diego's poisoning) but the real issue in my mind is that she did nothing after the fact.
Firstly, she could have spoken up after the kidnapping plot but did not. We could give her the benefit of the doubt and say that she didn't know that Dahlia was even alive, or that she could plead ignorance to what actually happened, but this is only the first incidence in a damning thread. Also, she still could have at least passed information along that suggested the kidnapping was not all that it seemed, given that Dahlia had tried to recruit her. And, if she believed Dahlia to be dead, what was stopping her from speaking out?
Secondly, and I'm putting her deception during her relationship with Phoenix to the side here for a second, why didn't she do anything when he was arrested for a murder he didn't commit? It's hard to be generous here because Iris was privy to all of Dahlia's plans (Violet, Fawles, Diego Armando) except the one involving Phoenix, but that's only because Dahlia kept her in the dark intentionally because Iris would have sabotaged it. However, she had to have been aware of what happened in the aftermath. Doug Swallows was murdered and Dahlia was, once again, at the center of it all. It was Mia, not Iris, who saved Phoenix. There's no evidence to suggest Iris was somehow unable to take action because she just went back to Hazakura afterwards. She never provides any excuse as to why she failed Phoenix when he needed her the most.
Now, back to Phoenix, here's where it gets fun. I am going to posit that her falling in love with Phoenix and wanting to protect him from Dahlia is for her benefit, not his. This is also, ironically, the first time Iris does something selfish. She fell in love with him and wouldn't let Dahlia kill him, but that's because for the first time in her life she wanted something. But I can't accept this protectiveness as romance. If she wanted what was best for him, she would have done something, anything either before this point or at the time of his arrest even if it meant getting into trouble. She, once again, chose to obscure the truth and instead did nothing.
Further to that, I can't accept her actions at Bridge to the Turnabout as anything but self-serving. She continued to hide the truth until it was presented to her. It was only at the eleventh hour that she confessed she loved Phoenix all along. It doesn't exactly inspire much confidence in her motives.
Now, all of this actually makes her a more interesting character in my eyes, so again, this isn't an Iris hate essay. She's tricky to get right in a Narumitsu context but here's a shameless plug to my story if you want to see my take on it: https://archiveofourown.org/works/63292576/chapters/162138757