He beats up Meat Boy and kidnaps Bandage Girl, which means Meat Boy needs to save her. When Meat Boy catches up to Bandage Girl, it only ends up with Dr. Fetus kidnapping Bandage Girl and teleporting elsewhere.
Through the use of developer mode a player can choose to play as Dr. Fetus. He features the special ability of throwing missiles and has the same movement as Meat Boy.
It should be noted that, in the manual that comes with the Ultra Edition of Super Meat Boy, there are diary entries that say "Keith Fetus 8.14.96." It is possible that Keith may be the first name of Dr. Fetus. His Twitter account also shows his name as Keith Fetus.
There is an item in Edmund McMillen's game The Binding Of Isaac called Dr. Fetus that is the called "Fetus in a Jar." It makes your character shoot bombs instead of tears, and wear a top hat and monocle. In the DLC Expansion, there is an item called Epic Fetus, which basically makes you the same visually (minus the eye brow) and allows you to hail down missiles.
Dr. Fetus makes an appearance in Super Tofu Boy, PETA's parody of SMB, where he is seen confessing to Bandage Girl and Tofu Boy that he put hormones on Meat Boy so he could act so violently.
As shown in a few comics, Dr. Fetus fiercely hates Meat Boy and kidnaps Bandage Girl to lure him through extremely dangerous paths.
His boss battle first starts with Dr. Fetus trying to hit the player with a homing rocket launcher. The player must run from Dr. Fetus, avoiding the plethora of saws, pits, and Dr. Fetus' missles. Then the player is trapped in a room with Dr. Fetus. There is a switch at the top of the ceiling. The player must dodge the missles shot from Dr. Fetus and hit the button. Then the player must run into another room and the floor will collapse, resulting in Dr. Fetus falling into a pit. When he lands, his glass jar will break, revealing his body completely. As he rolls around in pain and you finally reunite with Bandage Girl, he will press a button, causing "his castle" to start falling apart. Then the player must go all the way back through the level (although with some notable tweaks) with Bandage Girl piggyback riding you (this does NOT affect your movement) and survive to beat the boss.
- The animations for Dr. Fetus kidnapping Bandage Girl at the end of every level are based on other games.
- Hitting a button to remove the floor and defeat Dr. Fetus resembles defeating Bowser in the original Super Mario Bros. game.
- If the player manages to make it past the buzz saws on the right of the level during the first phase of the boss fight, they will NOT kill you after making it into the final room where Dr. Fetus falls to his near-death.
- Dr. Fetus is an item in the game The Binding of Isaac (another game from same creator)
- Dr. Fetus is the only boss that has a dark world variant.
- Dr. Fetus' name could be a reference to the villain Dr.Nitrus Brio (or Dr. N. Brio) from Crash Bandicoot.