Mr. Sinclair was a middle aged African-American man who lived in Hawkins, Indiana with his family. During his younger years, he was in a branch of the United States Armed Forces and served in Vietnam. This is implied by how his son Lucas often uses his father’s old military gear.
After leaving the Armed Forces, he met his future wife at some point prior to 1971, marrying her and starting a family where they settled down on Maple Street in Hawkins.
Mr. Sinclair, along with his wife and Lucas, attended Will's funeral.
Mr. Sinclair, along with his family, were having breakfast one morning in November 1984. While reading the newspaper, Lucas asked his father what he would do if his mother was angry with him. Mr. Sinclair told his son that he would apologize for whatever it was that he had done, and then he would buy her anything that she wanted. When Lucas asked what he would do if his mother was wrong, Mr. Sinclair joked that his wife was never wrong.
Lucas was in fact, without his father realizing it, stealthily asking him for advice on how to apologize to a girl, as he wished to make up with his crush, Max Mayfield.
|Season One appearances|
|The Flea and the Acrobat|
|Season Two appearances|
- He previously served in a branch of the US Armed Forces and fought in the Vietnam War. This is made obvious by how his son Lucas often wears and uses his father‘s old Military equipment.