Twin Freaks appears as a large, robotic simian head, with sharp metal hair and multiple ear piercings. It lacks a body, instead having four mechanical grappling legs with which to move within the long hallway.
It's first form is mostly green, with thick eyebrows and a pencil-thin moustache, and a wide, cheeky smile befitting the "funny" side. Ear rings appear on the tops of it's ears, and ear piercings on the bottoms. A full head of hair, with a hairline straight in the middle, and a thick beard are both present, the former less jagged looking than the latter.
It's second form is a scarlet red color, thin pointed eyebrows and a thick moustache to boot. Instead of a smile, it's always glowering, pointed teeth and half-lidded eyes adding to the "angry" side. The ear rings and piercings switch places, as well as the hair, eyebrows, mustache and beard, which gives a villainous look to the double sided machine.
Both forms share the same eye color, a golden yellow.
The machine appears in the scene named after it's soundtrack. In the US version, it pursues Headdy relentlessly without warning. In the Japanese version, Twin Freaks' job is to keep the hero from reaching Dark Demon, calling it an honor to stop a "scrap puppet" from getting to his emperor.
Throughout the fight, it continuously moves to the right, forcing Headdy to keep moving, lest he be killed. Twin Freaks also fires various small machines at the brave puppet to try and impede him. The arena doesn't make the task of defeating it very easy; Headdy must flip the hallway in order to procede, which also flips the boss.
Twin Freaks doesn't have any particular weak point; The "funny" side is vulnerable to Headdy's attacks, while the "angry" side is completely immune to any attack the hero has to throw at it.
In the US version, he can only be hit in the middle of the ear, and has 15 health. In the Japanese version however, he can be hit in the ear anywhere. But, to balance this, he has 30 health.