Chara was The first Human to fall into The Land Of The Monsters,  they were adopted into the royal dreemurr family and crowned as the unofficial, human heir to the throne right alongside their new brother.  The prince of The Monsters.  Asriel Dreemurr. Much like Frisk,  their personality is chosen by the individual person portraying them....  Alongside their gender.  Though i picture them as being ambitious.