The Binding of Isaac Wiki
This article is about the playable character. For the boss, see ??? (boss).

IsaacHD Xxx form2 Isaac Rebirth

???, also known as The Blue Baby, is an unlockable character in The Binding of Isaac. He is unlocked by completing the game 10 times, after which Isaac will find him locked in a chest during the ending cutscene.

??? is unique in that his health is made entirely of Soul Hearts and cannot be expanded with Heart Containers. This makes Soul Hearts the only source of replenishing health available to ???; standard hearts cannot be picked up and will remain on the ground as if the player is at full health. Items in the Devil Room will always cost three Soul Hearts while playing as ???.

Unlocking details

Due to the way the game counts "completions", players need only beat any of the endgame bosses—It Lives, Mom's Heart, or Satan—a combined total of 10 times to unlock ???. Since it is possible to defeat both Mom's Heart/It Lives and Satan in the same playthrough, ??? can be unlocked before the player has actually completed the game 10 times. However, defeating Satan requires accessing Sheol, which prior to unlocking It Lives requires either We Need To Go Deeper! to be used or for a Devil Room to be accessed after defeating Mom's Heart, neither of which are guaranteed to be available.

Items that work differently


  • Scapular: Gives a Soul Heart to ??? when he has none left, rather than when at a half heart as with other characters.
  • Whore of Babylon: As ??? is registered with no health by the game, the Whore of Babylon effect is always active on ???.
  • If you acquire an extra life via a 1UP, ??? will be revived with three Soul Hearts.
  • Any health increasing items (such as Raw Liver or Lunch) will only give the equivalent Soul Hearts to ??? instead of Heart Containers.
  • The Wafer: Reduces the cost of any Devil Room item to 1/2 Soul Heart, probably due to a bug where ??? takes damage to pay for items rather than lowering his (nonexistent) health.


  • Liberty Cap: Can get the "Odd Mushroom (Large)" effect which, instead of granting a Heart Container, will instead give ??? a Soul Heart and allow him to keep it. This effect will only work once and will negate the effect of the next health increasing item the player picks up. The Strength tarot card has similar effects.
  • The Polaroid: ??? will receive the invincibility effect whenever hit instead of the normal requirement of falling to one-half heart.
  • Cursed Skull: Will teleport you every time you take damage.
    • When combined with the Scapular, this makes ??? unable to die.


  • Full Health pills, Sacred Heart and <3 recover ???'s health to three Soul Hearts when he has below three Soul Hearts.
  • Health Up pills give one Soul Heart to ??? per consumption.
  • Bad Trip pills will heal ??? only if he is at half a soul heart (acts as Full Health pill).
  • As with regular Heart Containers, Eternal Hearts will turn into a Soul Heart when two are collected or a level is completed with one of them. The upside is that they will be used up at the very end, giving ??? a slight advantage in this aspect above other characters. (This is currently bugged, as losing all your Soul Hearts while having an Eternal Heart will still cause you to die.)

Items that have reduced/no effect


  • Charm Of The Vampire: Will only heal Heart Containers, rendering it useless.
  • Yum Heart: Will only heal Heart Containers, rendering it useless.
  • Little C.H.A.D.: ??? cannot pick up the half hearts Little C.H.A.D. drops, nor can effects like Mitre turn them into Soul Hearts.
  • Guppy's Paw: ??? cannot obtain Heart Containers, thus rendering the activated effect of the item completely useless.
    • The paw does however count toward the three items required to transform into Guppy, even though ??? is unable to actively use it. 
  • The Gamekid: Still grants invincibility and damage, but doesn't heal/give Soul Hearts.
  • Items that would normally heal other characters on picking up would also not heal ???. (e.g. PhD or Blood Bag)


  • Bloody Penny: Can only drop half red hearts, which are useless to ???.
  • Isaac's Fork: Will only heal Heart Containers, rendering it useless.
  • Child's Heart: The bulk of the added drops will be normal hearts, though a small percentage will be Soul Hearts.
  • Judas's Tongue: Doesn't lower the price of Devil Room items as trades offered to ??? is always at three Soul Hearts.
  • Umbilical Cord: ??? will only receive the familiar if/when he has no health, meaning that this trinket is useless to ???.
  • The Tick: Still takes 15% health off bosses; however it doesn't heal ???.


  • 2 of Hearts: The 2 of Hearts cannot double soul hearts, thus making it useless.
  • VI The Lovers: ??? cannot use the hearts spawned by this card.
  • XIX The Sun: Despite its Full Health effect, it won't heal ??? even if he is under three soul hearts.


Playing with ??? is a challenge, but his drawback also comes with upsides. His main gimmick relies on exploiting health based items or rooms.

There is a way to unlock ???'s items and achievements without actually having to play him. If you beat the boss in The Chest as a different character, but die afterwards (let the chest spawn, and then die) with the Ankh item, you'll respawn as ???. Completing the level will count as beating it as ???, giving you his Chest achievement, but still unlock the character specific item. If you are a different character that dies while they have the Ankh, they will respawn as ???. Besides if you have no "red hearts" if you beat The Chest (by deals with the devils for instance) and only soul hearts, the game will consider that you're both ??? and the character you chose, so you can unlock ???'s award and the chosen character's award.


  • The Devil Room/Angel Room have an increased chance of spawning for ??? as not taking Red Heart damage on the boss increases the chances of these rooms spawning.
  • The Devil Room will always offer items at the price of three Soul Hearts. However, certain items provide the player with Soul Hearts when picked up (The Pact with two, The Mark with one), making them more viable overall.
    • If you don't purchase anything in the Devil Room, the Angel Room can now spawn. Angel Rooms offer great items for free (especially the Mitre and the Relic), and they're not detrimental to ???'s health.
  • Since ??? only has Soul Hearts and cannot acquire Heart Containers, the usually risky condition of having only a half-heart or no heart containers left is always present.
    • Boss Challenge Rooms are always opened
    • Challenge Rooms are always opened.
    • The Whore of Babylon item will always be active.
    • Trinkets or other items that activate when the player is down to half a heart are active every time the player takes damage (The Polaroid, etc.).
      • Scapular is an exception, and will only activate when ??? reaches no soul hearts left. When this happens, ??? receives one. This effect can only occur once per room, to stop invincibility for ???.
  • While Eternal Hearts can only turn into Soul Hearts, it's basically impossible to lose them by taking damage (since ??? will die from having no Soul Hearts left at first).
    • Keep in mind that using the Blood Donation Machine, IV Bag or a Devil Beggar will still use up Eternal Hearts first.
    • For this reason, if possible, take Eternal Hearts before using the trap in the boss room.
  • Effects that temporarily grant the character an additional Heart Container will give ??? a permanent Soul Heart instead. Note, however, that this will put ??? at "negative" health, so the next health up he gains will put him back at "zero" health and give him nothing.
    • This makes the tarot card XI Strength particularly useful. 
    • The Liberty Cap trinket gives a random mushroom effect whenever the player enters another room. One of them provides a health up, but ??? can only gain one Soul Heart per playthrough in this fashion.

Tips and tricks

  • Buy Soul Hearts in Shops.
  • Make deals with the devil that give you items that give soul hearts (like The Pact, or The Nail)
    • Making a deal with the devil with exactly 3 Soul Hearts for those items won't kill you, but will still pop the death screen, forcing you to begin a new playthrough.
  • The Poop recharges with every room. Always use it, as even its minimal chance of providing Coins can make the difference.
    • Always pop the poop pile created by it before leaving the room, since it will despawn otherwise.
    • Consider using it as an obstacle for enemies or their projectiles.
  • Tinted rocks become even more useful because of the possibility of important Soul Hearts. Consider using your bombs on those instead of attempting to find the Secret Rooms.
    • If the rocks are adjacent to a wall, place your bomb in between the rock and the wall, to keep the possibility of opening up a Secret Room.
  • Having The Wafer allows you to make deals with the Devil for only half a soul heart, as long as you have at least 3 Soul Hearts.
    • This way, you can actually get additional soul hearts from the devil if you take items that give you soul hearts (like The Pact)
  • Curse Rooms have a high risk, high reward. You end up losing one Soul Heart (assuming ??? doesn't have Flight, or the ability to teleport back out), but have the chance of getting two or even four Soul Hearts back, acquiring a Devil Room/Angel Room item, Pills, and might also discover an adjacent Secret Room, or Super Secret Room.
    • You can check them out on the first floor and reset the playthrough if it didn't work out nicely.


Best Items

Good Items

  • D20 (can be used to reroll heart pickups into Soul Hearts)
  • <3 (will only recover Soul Hearts when ??? is below three Soul Hearts)
  • Full Health Pills (will only recover Soul Hearts when ??? is below three Soul Hearts)
  • The Tick (still takes 15% health off of bosses, but doesn't heal ??? and can't be removed as always unless you have Mom's Purse)
  • Blood Rights (When you have invincibility shields up)

Bad Items

Related Achievements




The Binding Of Isaac ??? ( End 13 )


  • As a 'secret' character, ??? is the only one not to be shown during the character selection until unlocked.
  • The character's alternate name is revealed on Isaac's Last Will, where it is signed "??? (The Blue Baby)".
  • This character is a nod to one of Edmund McMillen's Newgrounds submissions. On, McMillen is known as BlueBaby, and he has a series of "dress up" games titled "Dead Baby Dressup".
  • The "Blue Baby" syndrome is when a baby is born with cyanotic heart diseases, which can turn the baby's skin blue due to oxygen loss. This might be the origin of ???'s/Edmund McMillen's Newgrounds name. This is his homepage.
  • The item Fate is heavily implied to be ???'s severed head.
  • ??? can be seen during Dyspareunia, the final stage of Edmund McMillen and Florian Himsl's game, C-Word.
  • ??? is the only character in The Binding of Isaac who is not a biblical reference.
    • He is also the only unlockable character in-game who isn't Isaac dressing up.
    • Beating Sheol with ??? will unlock Forget Me Now which may be reference to ??? being a dead, secret/forgotten character in The Binding of Isaac.
    • ???'s starting item, The Poop, may be a reference to ??? being dead, and how people void their bowels when they die.
  • In the Wrath of the Lamb  expansion, many new bosses featured are posthumous versions of other bosses. They have similar, yet upgraded, attack patterns to their living versions. So naturally it would follow that when Isaac became a boss in the game, ??? would too. (??? would be the posthumous version of Isaac(Boss)).
    • In an inter-level cutscene, Isaac is in a chest and running out of air. This could be the explanation why ??? is possibly Isaac, but dead. In fiction, a person's skin can turn blue due to a severe lack of oxygen. This might explain why ???'s skin is blue and how it is connected to Isaac running out of air in a chest.
  • If one dies while playing as ???, the music will resume instead of the Today I Died... music.
    • However, this seems true for any character who's lost all red heart containers (e.g. through Guppy's Paw), and so died by losing their last soul heart.
  • When fighting one of the Seven Deadly Sins, ???'s name will come up as XXX.
  • ??? is the only character to have a different pose when he appears on the boss fight VS. Screen. Unlike all the other characters, who are curled up into a fetal position and laying on their sides; ??? is laying on his back, facing upwards. The same goes for his boss pose (as shown in the video below).
  • In the 10th Ending, when ??? look at Isaac, pure terror can be seen on Isaac's face. This emote is traduced by the fact he discovered his own death. At the same time, there's a time paradox due to the meeting of the alive and the dead Isaac.


  • When ??? gets hit, he shines with a "rainbowed" effect, like the one from My Little Unicorn (graphic bug)
  • When ??? gets killed, the game over music will not play. The current music will simply stop for a few seconds and restart.

External links

IsaacHDIsaacMaggyMagdaleneCainHDCainJudasHDJudasEveHDEveDead Baby???SamsonHDSamson