Ryan

Ryan was a British citizen, who lived and worked in and around London in the mid-nineteenth century.

Working as a barman aboard the 616 train between London and Cardiff, Wales, Ryan often stood in contact with the passengers. Among them was Vivian, a regular, with whom he worked to dupe rich businessmen, slipping sleeping pills in their drinks so Vivian could lead them to her sleeping carriage.

In 1868, Ryan slipped his sedative into the drinks of Matthew Killian and Angus Wolf, two wealthy industrialists. Vivian chose to take Killian as her victim, letting Wolf retire to his own sleeping carriage.

The following night, the Assassins Jacob and Evie Frye boarded the 616 train, interrogating all the passengers about the murder on Matthew Killian. Ryan confessed to drugging Killian, but denied any further knowledge of the crime.

Reference

 * Assassin's Creed: Syndicate - The Dreadful Crimes