A Hard Time
Tom goes along with the mutiny because he's here to have fun, and it is peak-Starfleet to leave a player in the brig for hours. Zero replay value.
But: as a mutineer, he's allowed on the bridge. So he sees his counterpart beside 'Kathryn' in the shuttle... and his expression, when 'Chakotay' shoots her in the chest.
He calls Kathryn to the holodeck.
After Tuvok comes clean, and Tom seizes the chance to bury—rewrite—evidence, he hangs back.
"Are we going to tell him?" he asks.
Wryly, Kathryn huffs a laugh. "About us? Seems to me he already knows."