Jeffrey

Jeffrey is a green and yellow passenger Robot Train. He is the mentor of Kay and the other Robot Trains in Season 1. Jeffrey was dropped in Season 2, despite the others returning in new roles

Season 1
Jeffrey watched as Kay prepares construction of the Intercontinental Railroad, concerned for its success as the construction is very risky. Later, he sees Duke returning alone, telling them that Kay didn't make it, only for the latter to return badly hurt. Upon hearing Kay mutter Duke's name, Jeffrey realized Duke was lying, and Duke prepares to attack Kay. Jeffrey assumes robot form and tries to stop Duke from coming by summoning a magnetic field. Duke was still powerful and knocks him away, only to witness Kay use up all of his and the Fountain Plaza's energy to defeat Duke. Jeffrey then locks him in the dungeon and keeps watch until Kay recovers.

Upon learning Kay has amnesia from being reformatted, Jeffrey took the time to reteach Kay about his duties as a Robot Train, usually contacting him every morning to tell him to head to the Fountain Plaza. He later helps Selly open up various worlds like the Mountain Area, later protecting the residents there by summoning a magnetic forcefield to destroy a fallen piece of rock that came from the broken clock tower. He was seen when Duke reappears, mortally wounded during the rematch between Duke and Kay. Jeffrey would later be seen fighting off the Duke clones.

Personality
Jeffrey is seen as an older, mentor figure, highly respected by Kay, the other residents of Fountain Plaza, and even Duke. He is wise and helps the other Robot Trains reopen up the other areas of Train World. Jeffrey can be also somewhat of a strict teacher who wants to see how important being a Robot Train is when he attempts to reteach Kay only for the latter to quickly get bored.

Abilities
Jeffrey, like Duke, is one of the larger Robot Trains in Season 1, however Duke is stronger than him as shown where he is able to pummel Jeffrey into defeat. Jeffrey has the ability to summon magnetic forcefields that can stop things from moving, although Duke is able to resist the force, and can even summon an electric forcefield to protect other trains from fallen debris. As Alf observed, his body is littered with training videos, making him a bit of a moving museum.