Given my recent push to draw more fanart, I wanted to emphasize the importance of interpreting existing characters.
It goes without saying that every artist has their own way of painting and drawing. This is especially true for established professional artists working on your favourite games and shows.
Every character and environment designed are under the vision of the designer. Every fabric fiber on the character, tree in the world, etc are all based off the experiences of the artists themselves.
If you understand this, by logic it also means that the design of a character largely functions around the style it was initially designed in.
A big part in creating fanart is to translate the character to what YOUR voice is. The reality is that because your voice differs from everyone else's, naturally trying to emulate them will result in a less than optimal result.
In other words, I am saying if certain details on a character or environment will look poor in your particular style, do not include them.
Every well-designed character will have iconic features which define them. As long as you include those features, you can omit (or sometimes include) certain things in order to make them look good in your style while keeping true to the original design.
Interpretation is very powerful and, ultimately, your goal is to create strong artwork even if you are limited by the original designs of your favourite IPs. Do not forsake appeal in order to force yourself to keep true to your favourite characters!