I like that idea! My only thoughts are how does that involve them totally not killing each other? also u doubt they'd ever fall in love but I'm sure they'd care for each other at some point. Jack isn't a total ass hole and Lexa I know cares deeply for people maybe even murderers with a cause. 

In any case I'm trying right now to contribute to the idea pool it'll just take a moment to figure something out....

Holy shit it just came to me. What if they end up being related??