Maria is arguably one of the most important characters lore-wise.

She was born in space (now retconned to being born on Earth) and loved gazing at the Earth through the ARK's window.
She was kind, selfless, intelligent, impulsive, brave, ambitious, empathetic, hopeful, and had a pure heart. She's good with emotions and good at comforting. She sometimes took on a more quiet and melancholy demeanor.

If someone insulted, dehumanized, or threatened Shadow, she became stubborn, angry, and bratty. She won't hesitate to yell at armed soldiers.
She often ignored her own health issues to the point that it even annoyed Shadow. She was physically frail, sick to the point of needing a wheelchair or an IV. Her personality was so strong people sometimes doubted she was ill. She was underweight but described as beautiful.
She found beings that are "gross/scary" cute or interesting instead. She's not very afraid even when she probably should be, but when she did become scared, she'd keep a level head. She's very perceptive and could figure out secrets that were kept from her with ease. She had the potential to be a scientific genius like Gerald and Eggman, she even designed Shadow's shoes.

Everyone around her seemed to love and coddle her, nobody truly hates her (except Black Doom), yet she was very lonely before Shadow was created. She enjoyed playing with Abe as if he's her little brother, but got annoyed with him quickly. She enjoyed being Shadow's guide in life and reading him stories. She liked giving hugs. She enjoyed books and learning about Earth.
Even while dying, her wishes were selfless. She wanted everyone to experience happiness and worth in their lives, especially Shadow, who she loved dearly and placed above all else.

It seems like a lot, but most of it is pretty surface-level. People will sometimes call her a shallow plot device.

So, that said: If you were tasked with giving Maria new personality traits, lore, likes/dislikes, etc., what would you add?