*Oof* Didn't these two have it rough…

At the start, Celestia and the others knew not to trust Discord but they still did (in a way) because they thought it would be pretty rude to not trust someone from their appearance/heritage.

And yea… they shouldn't have trusted him…

After Starswirl The Bearded gave the ones who were chosen alicorn magic and giving them the role to protect Equestria, Discord saw a chance to step in and take charge and claim Equestria as his own little playground, (he was doing this while Starswirl and the "other" five were in Limbo).

To try and get the spot from his fellow rulers he had to start off slow by manipulating them and gaining even more trust from them than before (especially from Celestia since she was head ruler).

The poor young princess ruler, she had alot of stress and responsibly on her shoulders without Starswirl's help, but with a bold and wise personality and her royal siblings to help she was handling her role *pretty* well, but not perfectly. Discord with his cunning personality jumped in and "helped" her feel more comfortable about her position.

Celestia did see a weird change in him, but she didn't bother it (and soon forgot about it). He was seeming much more charming than ever (but still keeping that abnormal stature of his). He was becoming closer to Celestia in a personal and more romantic way, that really tricked Celestia to make her think that Discord actually loves her.

It did shattered her heart when she found out that "that" wasn't the case, (And this was centuries later, so that relationship grew very strong for her, and somewhat Discord, but he chose the wrong and selfish decision; the aftermath is that guilt lingered in him still). This was when Discord was turned into stone (plus the banishment of King Sombra and Celestia's sister, Luna well Nightmare Moon, later on, but this was still in that era). Sooo… Celestia was basically going through great depression then (cue the "Celestia Being Deep" video)…