It accompanies the fun value theory:
http://napstamuse.tumblr.com/post/138312384562/gaster-the-grey-npcs-and-fun-values-an
I believe that Chara was one of the first to be given the ability to reset and go back in time. I theorize that Chara was one who suffered through a lot of heart-breaking moments and she used this power to fix everything.
Chara went back in time to make every situation good with his/her close friends), but he/she couldn't resolve them because there were too many instances of good situations turning into bad situations for others. This leads to why he/she hated humanity, becoming so corrupted that he/she wanted as much power as possible to end the human and monster race.
We can take from the the fun value theory, it is theorized that Gaster went to a very similar situation as Chara, testing certain outcomes that eventually lead to testing Genocide.
I believe Chara is connected to Gaster, in that he/she accidentally was given the power of resetting when Gaster first experimented on creating the power of resetting. I think Gaster wanted to create a reset power because he wanted to stop the war between humans and monsters. (Kinda feels obvious when you think about it)
Chara accidentally went back in time to the point before all these bad situations were placed onto her, letting her change fate. I believe that Gaster and Chara had equal power of reseting, leading to the time space continuom being corrupted, leading to Chara and Gaster's corruption. Leading to the plot of Undertale and how the game watches each and every action you make.
What do you think, is my theory flawed plot-wise. I couldn't get Chara out of my head and wanted to share badly.