I could've taken over the body of an adult, someone who was already strong and powerful. But I chose not to. I chose a child because not only their spirit was far easier to suppress, but also because he did not waste away a whole childhood and adulthood only to be possessed by someone like me.
—Darth Errol
Ahlecaine, also known as Reuel Ahlcain was the name of a Tyrrhan boy from the planet Tyrrha who lived as an orphan in the Dorne Teague Sanctuary. When the Sith Lord Darth Errol was freed from his holocron by Eezara Sol, Ricto Moran, Pol Poris, and Bennett Toomes on Coruscant, he chose the 3-year old Ahlecaine to become his new host body, and took possession of the child's physical form. The mind of the original Ahlecaine was completely suppressed, and his identity was used by Errol to infiltrate the Ministry of Science as a Republic citizen and later to build Gargan's Empire based on Ahlecaine's homeworld of Tyrrha.
Using Ahlecaine's body, Errol fathered two children with the Tyrrhan noblewoman Sil; Relharza and Sylaise, who were biologically children of the physical Ahlecaine, and so did not inherit Errol's Force-sensitivity. In 2292 BBY, the body of Ahlecaine died after the prolonged possession of the Gargan.