Perhaps calling Mariya an original character is a bit much? I like to think of her as my "mascot" of sorts, though even that word doesn't sit right.
Mariya is introverted, pensive and shy. Unless in good company, or enjoying her own.
I like giving her moe sweaters the most. I also really like her in pastel clothes, OL attire (she does have a corporate lanyard job in my imagination), anything weeby and cute. Tights or thigh-highs for ZR are something I like her in. Anything that fits old vaporwave/synthwave/etc sensibilities works great as well.
If you want to draw Mariya, you are more than welcome. R18 drawings are welcome as well. Feel free to use the hashtag #MariyaArt on Twitter.