Binding of Isaac: Rebirth Wiki

Disambig.png This article is about the boss. For the item, see Gemini (Item).

Gemini is a boss that can appear:

Each twin has 140 HP. The large twin is called Contusion and the small twin is called Suture.[1][2]


Gemini starts as a pair of bosses connected together by an umbilical cord.

  • Contusion chases Isaac and periodically charges increasing his speed, but stops to catch his breath afterwards.
  • Suture, while attached to Contusion, shoots a projectile towards Isaac if not behind an obstacle.
  • If Contusion is killed first, Suture detaches and begins charging furiously at Isaac. He has high momentum and takes extra knock-back from tears which can cause him to gain speed.
    • If Suture is killed first, there is no change to Contusion's behavior.

Champion Versions Needs to be unlocked[]

Cyan: Suture shoots homing shots. Contusion will drop a Soul Heart Soul Heart if killed last.
Green: They start separated from each other and have no difference in behavior. However, if Contusion is killed last, it will usually drop a Red Heart Red Heart or Half Red Heart Half Red Heart, but will rarely drop any other type of Heart instead (Soul, Bone, Gold, etc).



When fighting Gemini, the following obstacles can spawn:

  • Rocks in 4 different combinations
  • Rocks will always appear when fighting Gemini.


  • Gemini appeared in the original The Binding of Isaac.
  • Gemini seems to be an example of a parasitic twin, with Suture being the underdeveloped twin, dependent on Contusion.
  • Blighted Ovum Blighted Ovum is the posthumous version of them, and Steven Steven is the alternate version.
  • The Gemini pair is named after the astrological sign of the same name; the symbol of Gemini is a pair of twins.
  • The Gemini pair was originally designed to be a boss in Gish and was called Suture Contusion, with the larger twin being Contusion for the boot-shaped dent in his head.[2]
  • Contusion is the medical name for a bruise, whereas suture is the medical name for a thread used to close gaping wounds, commonly called stitches.
  • The names of the brothers are inspired by a song by The Mars Volta[1]
    • The specific lyric comes from "Cicatriz ESP."
  • In the Bestiary, Suture is referred to as "Gemini Baby".


Bug Bug! To unlock Cellar Cellar, Isaac must kill all Basement Basement bosses once. Gemini, however, counts as two depending on which part is killed first.
Bug Bug! If you Stun Suture at the same time that it tries to shoot Isaac, it will cause the sound effect to loop infinitely until Suture is killed.
Bug Bug! Removed in Afterbirth † If Gemini's chain hits Red Poop or Spikes, the chain will disappear but Contusion and Suture will still be joined.