Francis Sinclair is an enigmatic man with ginger hair and a large birthmark over his right eye. He speaks in a strange dialect, using slang that the protagonist does not understand.
Francis has combed, ginger hair and an orange pencil mustache. He appears to have quite a lean frame and has sharp, defined facial features, while appearing to be in late 20s or early 30s. He is seen wearing a checkered blue knit sweater over a white round collared shirt with a blue necktie, high-waisted and belt-looped khaki green tweed plus fours, argyle socks, and brown-and-white spectator shoes. These clothes are atypical for the time and setting in which he lives, adding to speculation that he may be some form of time traveler. Francis Sinclair has a strong Transatlantic accent, which was particularly prominent in American culture during the 1920s and 1930s. Sinclair's Business Card's logo has an hourglass with wings on it, symbolizing time and travel respectively. Francis wears trousers with belt loops on them, pants with belt loops were not invented until 1922.
However, this is not the first time Rockstar Games has introduced the concept of time travel in their games.
"Time Ranger" was a radio show that aired during the late-1930s, it narrated the adventures of Ernest Keigel, a man of science with a time machine in his pants, the Time Ranger. This show was first mentioned in Grand Theft Auto: Vice City Stories (2006).
Francis Sinclair shares numerous similarities with Ernest Keigel the time traveler:
1. Both have Transatlantic accents.
2. Both are fast talkers.
3. Both use 1920s and 1930s slang and are implied to have lived within the time period.
"Time Ranger" was a popular show from the 1930s. Francis Sinclair appears to have traveled to the Western from the 20s or 30s.
Coincidentally (or not), the plot of the GTA 5 movie "Shoulder of Orion II", which involves time travel, was stolen from the show "Time Ranger" (check the review). As previously mentioned by Strange Man in their video titled "5 Details Fans Haven't Noticed Yet (GTA 5)", the movie poster could contain a reference to both John Marston and Arthur Morgan, plus the Roman II being used in both sequels (RDR2 is a prequel, yes, but it is the second entry in the series, just like "Shoulder of Orion II").
From his unique birthmark, Francis appears to be a reference to Kraff, one of three false deities worshiped by the Epsilon Program from the Grand Theft Auto series, more specifically, Grand Theft Auto V. Francis also wears a lot of blue, like Epsilon Carpas.
It's really interesting to see how everything can be tied together. Btw, I'm not claiming that there's a bigger picture here, I just see these as detailed references to previous games developed by Rockstar Games.