Sentinel Academy

Tell me what lives in blue, in you. So I might tell you of guilt, of existing under duress, of questioning every day. The Talk came the day after college graduation, as expected. What wasn't, was the subject matter. Nathaniel had made a bargain at his death with the guards of impermanence, that he would attend the academy, in exchange for ten more years with his twin, Elyuana. The academy for sentinels that guarded the veil between the living realms and the...not.
And his decade was up. Content notes:Survivor's guilt; death of a loved one (before the story starts, but let's not kid ourselves about how it's on almost every single page).