I Miss You by Pantz
Summary: She was supposed to be his forever. Oneshot, 3,263 Words.
Why You Should Care: Totally anti-canon, written pre-HBP, but this fic is beautiful, sweet and bitter, and heartbreaking in a simple, practiced way. Percy is depicted with maturity and delicacy, and Penelope, who nearly falls into the trap of becoming a cliche, seems to gain a life of her own. Somehow the tragedy played out in this fic gets me every time.
Why You Might Not Care: …two Percy!fics in a row? Also, HBP and DH smashed the canon of this one.