I don't know anything about Invincible, but I know the feeling of not feeling able to write because of preassuring yourself and worrying that people won't like it.
Honestly, you gotta just say fuck it and fuck everyone and write. I deeply know the feeling of wanting people to like what I write, but you will never know how they feel if you don't post it and I assure you, you will sometimes be positively surprised. And you gotta remember that only you can see what you write in your drafts, so until you post it, you are the only audience, and you can go as crazy as you want.
And even if someone doesn't like it, so what? Fuck them. Write what you want to read, someone out there, even if it is just a single person, will tressure your writing.
I've had mulitiple slumps of writers block, and many of them were due to being scared that people wouldn't like my writing or the belief that my writing was bad. Remember that no one's first draft is perfect and that that is okay. Rome wasn't built in a day and all that. Focus on what you are writing in the moment, not if it is good or bad. We tend to be our own worst critic.
Something that has helped me before is setting a timer. At first five minutes of intensive writing, no editing, no deleting. That can get the flow of writing started, and sometimes makes new ideas spawn. I personally use this trick a lot. If you find that it helps, you can increase the number of minutes. I find that writing on a time limit is sometimes easier.
Another thing is changing your environment. We often tend to get stuck when we sit at the same place every time we write. Write in the living room instead of the bedroom, or maybe at a cafe or outside if the weater suits it.
And lastly, but most importantly, remember that you write because you enjoy it; focus on that. It is not their work, it is yours. And until you've posted it (and after also, really) you can edit and change it as much as you'd like. The good thing about creative writing is that there are free reins to do whatever the fuck you want.
I hope this is just a little bit helpful to you :)