Sam

Basics
Sam is the 'human' controlled by the player in Akintale. It has no personality nor thoughts of its own and has the same sex as the player. This means that its gender changes (which means they are by definition not genderless unless the player is) depending on who is playing, this can happen at literally any time if the keyboard/controller is passed over to another player. The colour of the Sam's eyes change colour depending on who is in control, blue when a player. The body is controlled by a strings connected to the hands, feet and the top of their head. As they are a purely a player character, they don't really have a surname but 'Pawn' is used.

True Pacifist
In a TP route, control is passed across to Frisk. The body's sex remains locked to whatever the player was even after Frisk gains control. The bodies eyes become green when Frisk is in control.

Genocide
When on a Genocide run, Chara never actually gains control over the body, they kill Sans, Asgore and Flowey with their own inhuman form. They only gain control AFTER the player gives them their soul. The eyes are red/brown when Chara is in charge, depending on their mood. Chara cuts the strings after a Geno, the body is destroyed with the world.

Neutral
When a neutral route is achieved, Sam is destroyed by the barrier as they are no longer needed. They never actually leave. This is why Sans judges them on every route except a TP and Geno.