Timothy (better known as Timmy) (まめきち,Mamekichi?) and Thomas (more often known as Tommy) (つぶきち,Tsubukichi?) are the twin employees of Tom Nook, the tanuki who runs the town's store. They are rumored to be his sons or nephews, and their last name is also listed as Nook. Certain jock or lazy villagers will tell of a rumor that Tom Nook found them in the streets and raised them by himself. Their full names were first revealed in New Leaf, when they are seen on the bulletin board during some shop upgrade announcements.
In the games where they appear together in Nookington's, the closest twin will become the primary speaker when choosing an item on the top floor.
Timmy and Tommy are raccoons (tanukis in the Japanese version). They are identical twins. They have brown skin with dark brown mask-like surface running down their eye area. They basically look like smaller versions of Tom Nook.
Tommy works Monday through Wednesday and runs the gardening floor of T&T Emporium.
Timmy and Tommy's most distinct feature is how one will echo the last phrase of the other when together. When alone in New Leaf they will also add a phrase at the end of the sentence in smaller text, though it does not copy the previous sentence's end like it does in previous games when they are together.
The twins share resemblance to Tom Nook, sometimes showing evidence of mimicking the latter's phrases. According to Tom Nook himself, the two can be distinguished by a mole on one of their hands.
Tom Nook also claims that he adopted them because they took an interest in business life, and that the twins are his pupils (in turn the twins refer to Nook as a mentor). Timmy is slightly higher pitched than Tommy.
Their German names Nepp and Schlepp are slightly misleading since "Nepper" and "Schlepper" in German language are words for con men and double-dealers. They were probably chosen for the amusing and rhyming effect. In New Leaf they are also used as puns, for example when they are running the "SchNeppchenmarkt". In this case parts of both names were worked into the correct spelling "Schnäppchenmarkt" to evoke a similar German pronunciation.
In New Leaf they eventually prefer being called Timothy and Thomas. That gives the assumption that they are slightly older and matured somewhat, or at least they want others to think that. The fact they start off capable of running the store with only one of them at a time, does imply they have grown up somewhat.
Timmy and Tommy are the new managers of the shop, which had previously been in the ownership of Tom Nook, who now works at Nook's Homes. At the beginning of the game, they will start off with Nookling Junction, having 4 upgrades as the game progresses, first being T&T Mart, next Super T&T, then T.I.Y., and finally T&T Emporium.
In T&T Mart, Tommy works in the day, and Timmy works in the night. The two have similar jobs to Tom Nook in prior versions of the game, as the player can buy furniture from them and sell items the player is carrying. However, the player cannot ask them about turnip prices or the catalog as in prior games. The player can sell their items to Timmy and Tommy, but the prices at which the twins accept items can vary.
Sometimes I think this house is too fancy for me and Timmy. We come from a humble background, yes. But then I look around and think we've worked hard to earn the right to live in such a palace!
-Tommy talking about the wonders of the house you built.
Timmy and Tommy do not have a professional role in Happy Home Designer. The player may build a house for them in any way they desire as their criteria for the house is simply "I'll leave it up to you!".
According to the Nintendo E3 Presentation, the Nooklings work alongside Tom Nook in the Resident Services building. One Nookling appears to allow players to buy and sell items while the other seems to be wandering around outside for an unannounced reason.
Little Timmy may look like a cute little raccoon, but behind those big, innocent eyes is the brain of a savvy businessman. When Tom Nook retires, his family business will be in good paws, that's for sure.
This little Nookling will be happy to help you at Nookington's, Tom Nook's supersized department store. But don't confuse Tommy with his brother Timmy. That hurts Tommy's feelings. And don't confuse Tommy with the grand poo-bah Tom Nook. That hurts Nook's feelings!