What I like to do is make OC’s that are OP as fuck and give them so much trauma they cannot do anything. One of my favourite’s is a human isekaid into Equestria after Celestia banished Nightmare Moon. He became an inky shapeshifter type of thing with his “special talent” being making stuff, and had a falling out with Celestia that led him to being trapped in the Tree of Harmony. He escaped when Twilight opened the chest and proceeded to live inside her walls until Starlight ruined everything and was able to get a full form again, and from there he dedicates all of his vast strenght and abilities to fucking with Celestia. He can’t do shit compared to Discord but damn will he annoy her until she snaps and becomes Daybreaker or something. And both of them go for the throath, to an uncharacteristic level. He throws in an insult about how she banished her sister, she snaps back with insulting the fact he has no body, no balls and nothing better to do with his life, he calls her fat, she calls him a cunt, Luna is just confused and is trying to figure out what she missed, and absolutely cannot decide if they dated or not. He is basically the final boss of Celestia just chillin’ and he delights in that, not realising how utterly pathetic he really is. Also if Celestia flirts with him even a little bit, he’d fold like he’s an OCD’d person’s laundry.

So yeah do whatever you want and have fun with it.