I think Leo's route is the most sad! Poor guy just wanted his love back, and messed it up then never got a chance to make things right! Plus I might have found a couple plot holes in his route!
Spoiler!
The whole train escape doesn't actually make sense. Why can the train leave the town and cars can't? Why would they believe a druggy and try such a dangerous stunt as jumping onto a moving train, even slow moving!?
Also they seem able to snap their friends out of the hysteria by talking to them and touching them, but nobody tried to comfort or reason with Leo! At least not a serious try. Chase although understandably having mental and emotional stress, didn't even try to tell Leo he was possibly having hallucinations even though it shouldn't be that hard to guess what was happening to him! Yeah Leo was being unstable and dangerous, but surly his life long friends could have taken a minuet to try and help him!