Subject 3 is a rabbit appearing in Professor Layton and the Unwound Future. He was one of the test subjects in Dimitri's lab, which gave him the ability to walk on two legs, as well as being able to speak. Subject 3's ability to speak has also given him quite the attitude. He is quite rude to Hershel Layton and Luke during the beginning of their adventures in Future London. Later on in the game he tells them of his sad story about how the scientists did tests on him. His name, Subject 3, is what the scientists in Dimitri's lab called him as well, so he decided to keep it.
When he was a baby rabbit, Subject 3 was picked for an experiment by Dimitri, possibly for the time travel machine. Separated from his family, Subject 3 was scared and angry. During one of the experiments, he was given the unusual ability to talk and in another walk and behave in a human way. At an unknown point he was either released or escaped the clutches of Dimitri. He came to the Thames river where he eventually met Layton and Luke.
Subject 3 also gives Professor Layton and Luke a few puzzles during their time investigating north Future London. The first puzzle he gives is "Rabbit Hops". The other is "Five Swimmers". He also gives, to Luke, a new Toy Car track.
- Subject 3 identifies the Parrot Luke owns as Subject 1, one of the animals tested before him, however, Subject 2 is never mentioned.
- Subject 3 is seen later behind a bush as the Parrot waves goodbye to Luke and Professor Layton, suggesting that he survived the explosion.
- In the tenth episode of Layton Mystery Detective Agency: Kat's Mystery-Solving Files, Subject 3 is seen as one of the accessories on Marina's handbag.
- His horrifying experimentation backstory and bad attitude resulting from it, is similar to Marvel Comics hero 's.