Monix

Monix the het ship between Mono and Six from the Little Nightmares fandom.

Canon
Mono and Six become close friends, working together to survive the dangers of the Pale City.

Mono meets Six in the Hunter's shack, where they learn to work together to escape.

Mono then risks his life to save Six from the Teacher and the bullies, and frees her from a trap.

Mono frees her from the Thin Man and the Radio Tower, is betrayed by Six, who leaves him for dead. Her betrayal likely drives him to target Six as the Thin Man.

Fanon
Most of the LN fanbase portrays a wholesome friendship between the two. Prior to the second game's release, the ship between Six and the Runaway Kid was the more prominent ship. Now it is likely the this ship most popular ship in the fanbase, though debatable.