Nicknames

So I'm making this character in this new game I got and I'm stuck on names her real name is Iris but it also wants me to give her a code name and I have no idea what to tell them I wanted to base it off of personality in which this is a game about an apocalyptic world hundreds of years in the future (I think anyway) and she's not hopeful for the future at all but she still wants to cater to people who are hopeful for a brighter future even though she doesn't believe it'll ever happen I want her to be a character with a more darker personality but probably more closer to someone who's just given up and is simply just fighting for the sake of others dreams I want something creative but also makes sense to the character but Google's not helping I've been sitting here over an hour trying to pick something and nothing is coming to my head so I was hoping you creative peeps could help me out? Please?