When you meet people, they form an image of you in their mind. These images are formed out of their perceptions, emotions, and memories of you, and it’s a hodgepodge that’s used to understand, predict, and react to your actions. In short, it’s their version of you. It’s who they think you are.
These images will never be an exact representation of you. People’s own biases and impressions go into them, and everyone has a different impression of you. Sometimes they’ll be pretty close to reality. Other times, they’ll be wildly different. Someone might have an image of you that’s angry all the time, but the reality is that you just have a “resting bitch face” and are perfectly calm otherwise. Their image of you as an angry person doesn’t mean you’re actually angry.
You don’t have to match any of these images. You’re you regardless of how other people see you, and nothing they think is going to change that. Images of you are not who you are.
If everyone sees you as a friendly person, that doesn’t mean you have to be nice or sociable. If someone sees you as a mentor, you’re not obligated to mentor them. If they think that you’re evil for liking the Muppets, it doesn’t mean you’re implicitly horrible. All that an image tells you is that someone sees you a particular way. It’s up to you to decide what to do with that information.
This is particularly relevant online, where it seems almost expected that you bare the depths of your soul in hopes of appealing to people. It’s an approach that might not be the healthiest or safest idea, and it all hinges on the idea that someone’s images have to be perfect replicas of them. Images will never be perfect replicas of you. It can be good to craft a more accurate image with close friends and family, but expecting strangers to get it right is absurd.
A corollary of this is that your images of others won’t be perfect either. This is particularly useful in conflicts. You might think that someone hates your guts, but that image of them might not be accurate. The only way to find out is to ask them what they really think (ideally without accusing them of hating you). Check whether your impressions are accurate, and a lot of conflicts turn out to be minor misunderstandings.