This series consists of stories set before, during or directly after the fourth season of MLP, which are canon-compliant as of the fourth season ender. They do not use book or comic canon.
They use Discord's backstory from The Last Draconequus.
Pre-Season:
Awkward Conversations: Takes place between "Keep Calm and Flutter On" and the beginning of the fourth season (and at least some chapters take place before "Magical Mystery Cure"), so it is prior to fourth season but intended to be canon-compliant to fourth season. Discord has a number of conversations with members of the Mane 6 and other characters. They do not generally go well.
Signal to Noise: Takes place between "Games Ponies Play/Just for Sidekicks" and "Magical Mystery Cure", so it is prior to fourth season but intended to be canon-compliant to fourth season. Twilight could possibly have forgiven the thief for stealing books from the library. But when she finds food stains all over a few the thief returned... oh, now it is on.
Princess Twilight Sparkle Endcaps: These are their own sub-series.
Intra-Season: Fics taking place during the fourth season, not associated with season opener or finale.
Love, Friendship and Chaos: Endcap to "Three's A Crowd". In which Discord hates his life, Cadance is a bit of a troll, and Twilight learns an important lesson about friendship and the concept of negative vs positive attention.
For A Few Parties More: Pre-episode to "Pinkie Pride". Cheese Sandwich meets Discord. Nuff said.
Post-Season: Fics taking place during or after the fourth season finale.
Traitor: The story of "Twilight's Kingdom" from Discord's POV.
No Escape From Yourself: Discord is afraid he'll fall again.