| Autumn |
Sanderson | The protagonist. Aka: Number Four, Lark |
| Hannah |
Vega | Claire's real identity, company owner. |
| Luis |
Vega | The real Mr. X, Hannah's husband. |
| Emilia |
Vega | Hannah and Luis's daughter. |
| Mr. |
X | The mysterious employer. Aka: Mr. X |
| Betsy |
| The nurse living next door. |
| Caleb |
| Autumn's colleague, a former IT employee. Aka: Francisco |
| Claire |
| Autumn's colleague, a former nurse. |
| Denise |
| One of the job applicants. |
| Elijah |
| Mr. X's right-hand man. |
| Evie |
| One of the job applicants. |
| George |
| Autumn's driver. |
| James |
| One of the job applicants. |
| Lincoln |
| Autumn's colleague, a former psychologist. |
| Paul |
| One of the job applicants. |
| Starla |
| One of the job applicants. |
| Sue |
| Mr. X's chef. |
| Tanya |
| Autumn's interviewer. |
| Vanessa |
| Autumn's colleague. |
| Victor |
| Autumn's colleague, a private investigator. |
| Maureen |
| Mr. X's housekeeper. |
| Lila |
| A longtime guest. |
| Gloria |
| One of Autumn's colleagues. |
| Jean |
| A girl Autumn helped. |
| Soph |
| One of Autumn's colleagues. |
| Doreen |
| One of Autumn's colleagues. |
| Elizabeth |
| One of Autumn's colleagues. |