The Siren

The Siren is a monstrous boss encountered near the end of Lost in Vivo, an indie horror game developed by Akuma Kira.

The Siren's exact purpose, origin or symbolism is unknown, but it's possible it might act as either a kind of trial or a manifestation of the Protagonist's phobias and fears.

Appearance
The Siren is colossal compared to most other threats seen during the game. It's a legless humanoid creature with pale, putrid skin, and the creature appears to be emaciated, with it's ribs clearly visible through it's chest.

The Siren lacks proper eyes, and instead, there are two, twisted mouths, which seem to be laughing and smiling constantly. The nose itself is completely missing, leaving the creature's gaping nasal aperture visible.

Behavior
The Siren is fought in three stages, where something different must be done to drive the creature away.

The Siren erratically changes from fast to slow crawling, which may make it difficult to evade it or exploit one of its weaknesses.

The three methods are outlined in pages, torn from a book about spooky stories for children. The three encounters are listed as follows;

Spooky Stories for Children, Vol. 1
After the Player accomplishes an objective, the Siren will emerge from a sewer pipe sealed off with chain link fence, and begin to chase the Protagonist. The Protagonist must lure the Siren over a catwalk suspended over a pool of water, with wires running from an electrical breaker danging into the pool.

Then, the player must flip the breaker switch, electrifying the water and delivering a powerful shock to the Siren, who thrashes and is driven off.

Spooky Stories for Children, Vol. 2
After accomplishes yet another objective, the game suddenly switches to the viewpoint of the Protagonist's lost dog, Dani, as they wander around the sewers.

Pressing Space will cause Dani to bark, resulting in the Protagonist whistling. Using this, the player must guide Dani all the way through the sewers, using the whistling as a method of direction.

However, upon reaching the door of a floodgate, the screen will rapidly glitch out and turn red, with the Siren's claws seen reaching toward the door. Back in the control of the Protagonist, the player must switch on the floodgate, blasting the Siren with water, who is mimicking the sound of Dani's barking and whimpering.

If the player does not turn on the floodgate, the Siren will burst through the door and kill the player.

Spooky Stories for Children, Vol. 3
Upon completing the final objective, the Siren will emerge from a pipe as the player attempts to make their way back, chasing them around a maze-like area with multiple pillars and a heavy, steel blast door. The Player must manage to open up the blast door and drop it on the Siren as they pass under it, pinning the Siren down.

Then, with the Siren pinned, the player must then wail on the Siren with their most powerful weapon, (the Sledgehammer, or if playing through New Game+, the Double-Barrel Shotgun or Fireaxe), until the Siren simply cannot take any more, thrashing and crying before the blast door crushes their body, killing the beast.

However, the Siren has one more trick up its sleeve. It's mutilated face will bulge out before bursting open, a infantile monster called Childhood Memories crawling out and toward the player while wailing and screaming. A single blow from any weapon will silence it for good.