Robin to me.
Her mother left her at a young age.
Her Aunt treats her like crap, and the village people hate her because of her Hana Hana no mi
The only people who she could talk to were the scholars
When she eventually was able to be an aecheologist they wouldn't let her dream of helping them come true. She had almost worked so hard for nothing.
Just when she meets a real friend (Saul) the marines show up and kill everyone she cared about and her home.
She meets her mom and right after that she dies.
She then had to spend her whole life alone until she was 28, and then she almost had to give up the one thing she wanted (family) in order to keep them from dying.
Ace had Luffy and for a time Sabo, and he had the White Beard Pirates.
Nami at least had the Scared up Officer and her sister (blue haired chick)