Honestly, Iris seems like the same type as Cas to me. She's quick to help other people but also withdraws when she's stressed (2s do that to conserve energy when they don't feel like they're able to be there for others). She agreed to assassinate Cas to please her dad just like Cas follows orders to make his father happy. She struggles with feeling unworthy of love and affection, which is what all 2s feel on the inside even if they don't admit it, and tries to earn approval from other people to fill that void.

Here's a blurb on 2s in relationship with other 2s: [url=https://www.enneagraminstitute.com/relationship-type-2-with-type-2]clicky[/url]
I think it describes Cas and Iris pretty well, but maybe you see it differently :)

As for the prison thing, I don't think she would end up back there again. At least, if she does, it won't be for a while. Cas would never give her up to the military even if it means he has to suffer, so she's safe with Miles at the moment