He first appears during Brittany's show, Fondue For Two, where he eats the food. She later interviews Lord Tubbington, when Santana stands Brittany up.
Lord Tubbington is seen during Marley and Brittany's Fondue For Two segment. Marley says he is thinking that he wants to lose weight and has a gambling addiction. He is also seen during This is the New Year.
Brittany belives that an asteroid is heading towards Earth, and infroms New Directions that they should say goodbye to their last ones. Lord Tubbington is first seen in Brittany's room, as she tells him that through everything, she's loved him. Sam suggests that the group could sing to him, and she agrees. New Directions sing More Than Words for him. Thanks to Sam, he now has a lady friend named Lady Tubbington.
When Marley tried to perform her *pet psychic* powers on him, she guessed that he was trying to lose weight, along with him having an online gambling addiction. This was denied by Brittany, but it may be true.
Trivia
In New York, Brittany buys an extra large t-shirt for him.
He has probably been judged by Jesse, as agreed to in Funeral.
Lord Tubbington's weight of 25 pounds is a reference to Bustopher Jones from T.S. Elliot's book Old Possum's Book of Practical Cats and the Andrew Lloyd Webber's musical Cats, which is based on the aforementioned book.
In On My Way, Brittany mentions that she looks forward to the day when Lord Tubbington kicks his "ecstasy addiction."
In Saturday Night Glee-ver, he is featured on Brittany and Santana's released sex tape doing everyday household chores. The video is called "2 girls, 1 cat."
Brittany accuses him of doing many things that would be impossible for a cat, such as smoking, going to jail, reading her diary, and joining a gang. However, it is possible that Lord Tubbington is very smart since he was seen doing chores in Saturday Night Glee-ver.
In Britney 2.0, he is on Brittany's bed wearing a leather jacket and shade glasses. As of that moment, he and Brittany are no longer on speaking terms because she believes that he has joined a gang.
It is still unknown who put the jacket and glasses on him.