Supernatural: Dean/Sam.
Written after Salvation but before Devil’s Trap, this goes AU before the season 1 ending but it’s a gorgeously executed look at what could have happened if Sam and Dean hadn’t gotten to Papa Winchester in time to save him. Dean and Sam’s characterization is great in this; Sam and Dean always seem like the kind of characters whose best (and worst) qualities come out in times of crisis and Liz totally understand this.
Carry On by