Both of Me by Jonathan Friesen

Two teens who seem to be trying to escape the lives they have thus far lived meet after Elias accidentally takes Clara's back pack when he deplanes.  The two sat side by side and had identical
pack packs.  Clare goes to retrieve hers and return his.  Instead the pair head off on an adventure to find the lightkeeper.  Elias has multiple personality disorder and it is his alternative personality that is in charge of the journey.  Clara has been traveling around the world to countries and cities described in her father's journal of his own adventures.  Clare at least sort of hopes to help Elias put both parts of him together.  Following stars and myths and her father's journal the pair set off for one place after another seeking the evil lightkeeper and ultimately to destroy it.  The journey takes them through a series of towns called Salem in several states, into the underground railroad.  They meet a variety of interesting people and eventually find what each was truly seeking, though not perhaps what they thought they were seeking.  Like Jerk California the story focuses more on the characters than on the disease that affects  them.  Teens who enjoyed Jerk should enjoy this story as well.
jdw3/19/15