I can absolutely see Harmony and Tristan running around together. The Partner in Crime line you have would actually fit Tristan preeeeeetty perfectly. He's based off Enjolras from Les Miserables, and idk, I can just see them hitting it off. He's also been in jail before so there's that. Let me know if you're up for plotting!
Idk if Harmony and Lain (theladyamalthea) would be around each other much but you never know! She's based off The Unicorn/Lady Amalthea from The Last Unicorn.