Halo: Bad Blood is a print novel by Matt Forbeck and is part of the Halo Expanded Universe. It is a sequel to Halo: New Blood and takes place after Halo 5: Guardians.
Just hours following their climactic battle on the Forerunner planet Genesis, the Spartans of Blue Team and Fireteam Osiris find themselves running for their lives from the malevolent machinations of a renegade artificial intelligence. But even as they attempt to stay one step ahead, trouble seems to find Spartan Edward Buck no matter where he turns.
A secret mission enacted by the Office of Naval Intelligence could possibly help turn the tide, and has Buck reluctantly agreeing to reform his old team, Alpha-Nine. Because if the band is really getting back together for this one, that means everybody—including the Spartan who Buck never wants to see again, the one who committed the ultimate betrayal of trust.
- The Bad Guy Wins: Cortana not only secures Hole in the Wall and its method of concealing itself from the galaxy at large but has conquered most of the galaxy already.
- Big Bad: Cortana has taken over much of the galaxy with the power of her fellow A.I.
- Bittersweet Ending: Cortana manages to track down Hole in the Wall and conquers it with a Guardian. Our heroes barely manage to escape. On the other hand, many of the colony's scientists escape, bringing with them possible knowledge of how to fight the Created.
- Easily Forgiven: Arguably Mickey, who never changes his opinions in the slightest and betrayed the team in the previous book. Buck asks him to be reinstated as a Spartan-IV.
- Glad-to-Be-Alive Sex: Upon discovering both had survived the initial Created uprising, Buck and Veronica Dare engaged in this when the latter returns to the Infinity with Blue Team and Fireteam Osiris.
- The Heavy: Leonides serves as the secondary antagonist of the book, being the A.I. that served as the Spartan-IV program's supervisor.
- Late-Arrival Spoiler: Cortana is the Big Bad of Halo 5: Guardians.
- Putting the Band Back Together: The point of the book is reassembling Alpha Nine (sans Rookie) to take down Cortana.
- Your Terrorists Are Our Freedom Fighters: Pretty much the point of the book as the Insurrection has become a potential ally against Cortana.
