Just In Case by Meg Rosoff
Justin Case is convinced fate has in for him.
And he’s right.
After finding his younger brother teetering on the edge of his balcony, fifteen-year-old David Case realizes the fragility of life and senses impending doom. Without looking back, he changes his name to Justin and assumes a new identity, new clothing and new friends, and dares to fall in love with the seductive Agnes Day. With his imaginary dog Boy in tow, Justin struggles to fit into his new role and above all, to survive in a world where tragedy is around every corner. He’s got to be prepared, just in case.