When people heard the voice of John De Lancie for the newly-introduced antagonist in season 2, Discord, the spirit of chaos, fans went nuts for him.
Since then, every episode with this draconequus is always known for being funny and having a ton of references to other medias.
In "Return to Harmony", he acts as the antagonist by hiding the elements of Harmony, trying to divide the mane 6 and turning Ponyville into Chaos Capital of the world, we all know how his plan turned out.
In "Keep Calm and Flutter On", Princess Celestia ask the Mane 6 to help reform Discord so he can use his powerful chaotic magic for good, and she believes Fluttershy will be the one who can reform him. Fluttershy thinks the best way to reform Discord is to befriend him, At the end, Discord does promise to use his powers for good (most of the times) because he treasures his friendship with Fluttershy, but not enough to not betray them when Tirek offer him freedom for an alliance, only for Tirek to betray him.
Since the elements of harmony are now returned to the tree of harmony, Equestria has lost one of their powerful defenses. Since the elements and the power of the tree is the only way to defeat Discord, it shows how powerful he is so it makes sense that Princess Celestia wants Discord to use his magic for good.
Discord can sense magical imbalances, transform and create things out of thin air and break reality itself.
That's his role in Equestria but what about in the show?
Twilight in the beginning refers to people who don't really care about friendship, as more of an antisocial person. Discord represents a different kind of person, he represents the kind of person who doesn't know much about friendship. It's not because he doesn't care, he doesn't understand how friendship fully works yet, he doesn't know what's okay and what's not when it comes to friendship, no episode shows this better than 'Make New Friends but Keep Discord'.
Discord gets green eyes of envy when he learns that Fluttershy has a new friend called Treehugger when she went to observe the breezies and that Fluttershy asked Treehugger to go to the Grand Galloping Gala with her instead of Discord.
Feeling like he has been replaced, he gets his ticket and goes to the gala with a sentinel green goo creature called the smooze to make Fluttershy feel jealous too.
But when things don't go his way, he tries to send Treehugger to another dimension so he can have Fluttershy's friendship to himself.
Eventually Fluttershy steps in and tells Discord it's normal to have more than one friend and have different friends for different things. People think that seems out of left field for Discord, seeing how he normally portrayed as smart and calm while playing somebody else, but they seem to forget he is new to friendship.
He doesn't understand that people can have different friends for different things, he is scared that he may be replaced so he becomes a little possessive towards Fluttershy. It may seem like a kid moral but there are people who are like him, most of them are children or teenagers that are shy and insecure about themselves and their friendships.
While this moral may seem useless to us, it could be a new way of seeing thing or a long-needed answer for those people.
Anyways, that's all for now, feel free to voice your thoughts and opinions.
See you next time.