X!Tale Undyne

A videogame:
It is a world where humans and monsters coexist. Long ago, there were human souls, classified by: Integrity (a blue soul), Kindness (a green soul), Patience (a light blue soul), Courage (an orange soul), Justice (a yellow soul), Perseverance (a purple soul), and the strongest, Determination (a red soul, and the strongest, being the player's soul, with the ability to do resets, or save games, like in games.)

She is the alternate version of Undyne from Undertale. She belongs to an alternate universe, whose history is deep.
She is the captain of the royal guard. She is a fish-like monster with white skin, long purple hair tied in a ponytail, a black patch on her left eye, pointed teeth, black eyes with white irises, white armor with a black scabbard with black details.
Age: +50 (Unknown, but she is quite old)

XTale was a peaceful au, but XGaster, the creator, corrupted it and began to erase and write the Au's timelines, making everyone forget. XUndyne was the captain of the royal guard.
XChara was the prince and his student to defeat XGaster, and she serves XAsgore and XToriel, king and queen. XFrisk and XAsriel are the other princes of the city. XAlphys was her love interest and partner.

But in the last timeline, Everyone found out what XGaster was doing, and everyone was under XGaster's control, including XUndyne.

She likes to fight, and she likes watermelons

She doesn't like annoying people.

Lesbian (She is attracted to other women)

XTale erased all alternate universes, leaving only the original universe. XUndyne is being controlled by its code, and she's ordered to kill and capture the enemy.