Ouroboros

Ouroboros are entities in Xenoblade Chronicles 3. They take the form of giant, vaguely-humanoid entities with a purple hue. Two characters with an interlink may temporarily combine to take on an Ouroboros form.

As a gameplay element
Each of the three interlink pairs among the main playable characters ( &, & ,  & ) may (independently) combine into Ouroboros form during combat. This changes the moveset made available to them.

The form of the Ouroboros taken, as well as the moves made available as a result, depends upon which member of the pair takes the lead. This may be swapped at will; for example, if Noah and Mio are currently in Ouroboros form, the form and moveset may be swapped between that of Noah's Ouroboros and that of Mio's Ouroboros.

Trivia

 * Ouroboros forms are very similar to the Gears in Xenogears.
 * Noah's Ouroboros form is similar to Weltall.
 * Lanz's Ouroboros form is similar to Brigandier.
 * Eunie's Ouroboros form is similar to Vierge.
 * Sena's Ouroboros form is similar to Crescens
 * The name 'Ouroboros' is a reference to the symbol of the same name: a dragon or snake eating its own tail, commonly interpreted as representing eternal cycles. This symbol is also seen in Xenoblade Chronicles 3.