Part 1
—This story was partially inspired by the Sherlock episode The Reichenbach Fall.
—Discover Check Chess Club: a discover check is when a piece moves aside to get out of the way of a rook, bishop or queen, placing the king in check.
—"Wunderbar": German, "wonderful."
—"dummkopf": German, "idiot."
—Zugzwang's concealed blade in his sleeve is inspired by the Assassin's Creed video games.
—"schweinhund": German insult, literally translates to "pig-dog."

Part 2
—Lemon juice is a common invisible ink. It becomes visible when exposed to heat.

Part 3
—Beethoofen: play on Beethoven, a German composer.
—Canter Nostra: play on Cosa Nostra, the proper name for the Italian Mafia.
—Japonese Yakuza: reference to the real-life Japanese Yakuza organized crime groups.
—Sinalope cartel: play on the Mexican Sinaloa drug cartel.
—Mareish Mob: play on the Irish Mob.
—"Mein freunds": German, "my friends."
—"liebling": German, "darling."
—Zugzwang revealing that he knows about Phillip's past is similar to the scene in Batman Beyond: Return of the Joker in which Joker reveals that he knows Batman's identity.

Part 4
—A caduceus is a winged staff with a pair of serpents, a symbol of the Greek god Hermes, and often incorrectly identified as a symbol of medicine and doctors.
—Winged Cure's tattoo bears a similarity to the Dark Mark worn by the Death Eaters in the Harry Potter series.
—In the Phillipverse, Flash Sentry grew up in the crime-ridden slums of Fillydelphia.
—"we both know one of us is going to kill the other one day:" the only way Phillip and Zugzwang's relationship can end.
—"Viel Glück, liebling!:" German, "good luck, darling!"

Part 5
—"The biggest mistake an Investigator can make is to make theories before they have evidence. You end up twisting the facts to support your theory instead of adjusting your theory to support the facts.": paraphrasing Sherlock Holmes in A Scandal In Bohemia.
—Curiouser and curiouser...: reference to Alice in Wonderland.
—Flash's scar is from an injury in a previous story, Secret of the Mare Lisa.
—"Ripper.": Australian slang, "great!"

Part 6
—Strychnine is a poison, often used in rat toxins, that causes violent muscle spasms and respiratory paralysis. It's a slow, agonizing way to die.
—Zugzwang's final thoughts reflect his obsession with Phillip.

Author's Notes:

Chapter notes from the story.