Finn Hopkins is the son of Sadie Hopkins.
Appearance
Finn was a curious boy on the train who eventually wandered to the back, seeing Gillies. The policeman on duty didn't see him, as his back was to the lad. Gillies attempted to persuade Finn to stealing the keys for him, promising $5, however the return of the constables prompted Finn to leave and Gillies to back down.
After these events, Finn most likely slept through the most of the episode, as he didn't realize the gravity of the situation around him.