Gideon Cahill was the found of the Cahill family and the father of the founders of the five Cahill family branches.
Gideon and his wife, Olivia, lived with their four children on an island in Ireland back in the late 1400s. Gideon was a great alchemist who actually created a serum that granted the drinker unbelieveable skills and abilities. However, in 1507 when Gideon drank his serum he realized that his creation was killing him. He split his serum into four groups and gave each of his children one group of ingredients that when consumed, would grant the drinker amazing abilities. His eldest son, Luke, got the part of the serum that made him ruthless, sneaky, and stealthy. His eldest daughter, Katherine, got the part of the serum that gifted her with amazing intelligence and intellect. His son Thomas got the part of the serum that made him extremely strong and athletic as well as brave and courageous. His youngest child, Jane, got the part of the serum that made her very artistic and musical. Luke was upset with his portion of the ingredients because he thought that he deserved the most as the oldest.
While he was trying to create a fifth portion of the serum so that it wouldn't kill him, his old friend, Damien Vesper, who had gotten jealous of Gideon, came to their island and tried to steal the formula. However, Damien was unsuccessful so he set the Cahill home on fire which killed Gideon. Katherine and Thomas blamed Luke for the fire which made Luke leave the island and travel to London. Katherine and Thomas left together and tried to keep moving because they thought their brother was trying to follow them to steal their clues. Jane left last and went to Italy.
Gideon died before he found out that his wife, Olivia, was pregnant with a fifth child, Madeleine.
Gideon Cahill was presumed to be an older man because of his description. He is said to have wild gray hair that wasn't ever combed or brushed. His face was darkened from years of working in his laboratory. His forearms had notes written on them and he had a golden ring, that is still in the Cahill family to this day.
- Madeleine the Matriarch (great grandmother; deceased)
- Olivia Cahill (wife; deceased)
- Luke Cahill (son; deceased)
- Katherine Cahill (daughter; deceased)
- Thomas Cahill (son; deceased)
- Jane Cahill (daughter; deceased)
- Madeleine Cahill (daughter; deceased)
- Louisa (daughter-in-law; deceased)
- Keiko (daughter-in-law; deceased)
- Winthrop Cahill (grandson; deceased)
- Toyotomi Hideyoshi (grandson; deceased)
- William Shakespeare (great grandson; deceased)