|“||This is what has ruined our world ten times. I'm tired...but I'm forced to use this power||„|
|~ X-Event!Frisk explaining to X-Tale!Sans what's happening with his world|
OVERWRITE is a very powerful tool, designed from a modification of the power of resetting. It works with a tap of its button; it'll allow any user to change the reality of a timeline, as well as any thoughts, actions, memories, and roles; for example, changing how someone will die, like what happened when it forced Underswap!Papyrus to stab himself and Underswap!Chara. However, it's power is abusive, and too much of it will eventually break down the timeline, or the AU itself if one has a full overwrite soul. It is derived from a form of the Perseverance soul trait.
Overwrite is fairly limited though. With only half of the ability, one cannot overwrite an AU, nor the multiverse itself. It can only corrupt one timeline, and the code that follows, and is not guaranteed to be permanent. Also, overwriting anything without a specific code, or an original character is impossible to do so. It can also be broken by a user but this is only possible when it’s in its complete form.
The three main users, XGaster, X-Event!Frisk, and X-Event!Chara, all use it for different purposes: XGaster uses it to bring in the deaths of X-Event!Frisk's and X-Event!Chara's loved ones; X-Event!Frisk uses it to get X-Tale!Sans's genocide code back, and eventually uses it to bring back everyone's memories and kill XGaster; X-Event!Chara, meanwhile, uses it multiple times to mess around with stories of other timelines. He even wants the other half of XGaster's soul (located within Ink!Sans's white vial) to eventually allow him to corrupt every AU, which would cripple Ink's intentions of protecting them. This is the main reason why Cross sealed X-Event!Chara into his soul, to prevent him from ever overwriting again. However, once he's knocked out, Cross!Chara takes 95% of Underswap!Chara's soul, allowing him to overwrite once again. However he lost the ability to overwrite when Nightmare!Sans killed Underswap!Chara weakening his stolen soul. However once XGaster is reawakened he gains the complete Overwrite.
- This is exactly what happened with X-Tale and the Underswap pacifist timeline at the ending of Underverse 0.3 Part 2: https://youtu.be/MA_o7lEs6cc?t=24m40s
- https://www.youtube.com/watch?v=PhX2TbX7d_s In the description