When Gus and the other alien sympathizers are granted psionic powers as acolytes of the hive mind, Sam realizes something needs to change – and that something is him. So he gives in to Ronan’s personality, which was imprinted onto him as Ronan died, letting it take over entirely.
Ronan had none of Sam’s people-pleasing tendencies, so the imprint gives Sam a confidence boost. But it also makes him headstrong and foolhardy. He goads Gus into a hasty attack on the hive that results in Gus starting his own break-away faction: The Gus Ascendancy.
Before Sam’s consciousness is completely overwhelmed by Ronan’s personality, Journey finds a way to psionically scour most of Ronan’s imprint away. Sam has just enough confidence left to negotiate a compromise with Gus.