Binding of Isaac: Rebirth Wiki

???'s Only Friend is an unlockable passive item.


  • Spawns a controllable familiar that damages enemies on touch. It can be moved using the shooting directional keys, similarly to The Ludovico Technique The Ludovico Technique and Robo-Baby 2.0 Robo-Baby 2.0.
    • Removed in Repentance ???'s Only Friend deals 2.5 damage per tick, and ticks 15 times a second, dealing a total of 37.5 damage per second.
      • Added in Repentance ???'s Only Friend deals 3.5 damage per tick, and ticks slower.
  • This item belongs to the Beelzebub set. Collecting three items from this set will transform Isaac into a giant humanoid fly.


  • Unlike The Ludovico Technique, it cannot be controlled with the mouse, even with mouse control enabled.
  • Holding two opposite fire keys (both left and right or both up and down) at the same time will keep the familiar in place, while making Isaac fire in the direction of whichever fire key was pressed second.
    • This can help during combats with bosses who do not move a lot, as the familiar can continuously damage the boss when kept stationary.
    • On some keyboards, holding opposite fire keys may cause other keys to become unresponsive.

In-game Footage[]



  • The sprite for the familiar resembles a Boom Fly Boom Fly.
  • This item is slightly faster than Robo-Baby 2.0, but is only noticeable when rapid clicking the tear button.


PC Normal mode only HC7F QZAT (Treasure Room adjacent to spawn)

PC Normal mode only J6S4 VMQM (Treasure Room adjacent to spawn)

PC Hard mode only 6CQZ CL2Y (Treasure Room adjacent to spawn)

PC Added in Afterbirth † Normal and hard modes only 0CN2 GSH1 (Treasure Room adjacent to spawn)

PC Added in Repentance Hard mode only 947Q 4JAN (Treasure Room adjacent to spawn)

PS4 Y4FW NYCX (First floor treasure room)

Switch Greed mode only 6RS1 FT1H (First Golden Treasure Room)