Not knowing that Eddie just told Katherine that he is the father of Delilah's baby, Theo surprises his mother in the living room, and she breaks a plate. As she tries to keep up the appearance of being fine, Katherine announces to Theo that they will cook cookies, which rejoice the young boy. For the rest of the day, Theo and Katherine cook together. However, that night, Katherine is unable to keep the act and asks Theo to call his father. Theo obeys, telling Eddie that Katherine wants him to come back home. Then, Katy asks Theo to watch something on his tablet for the next 30 minutes, as she leaves the house before Eddie's return. For the next two days, Eddie is unable to contact Katherine and keeps telling Theo that she is absent because she works on an important court case. The young boy misses his mother a lot, but Eddie continues to pretend that everything is fine in front of his son. Theo also ordered a gift for Delilah's baby, still ignoring that she is his half-sister. Eddie eventually discovers that Katherine is hiding at her mother's house, but is unable to convince her to come back home. That night, Eddie and Theo make cookies, as they hear someone coming to the door. They both get excited thinking it is Katherine, only to be disappointed when they realize it is a man delivering Theo's gift for Charlie. ("Coming Home")
Theo with setting the table and set a spot for his mother in the hopes that she would come home early from her court case. Days later when getting ready for the gardening event, his mother surprised him and came home through the front door. He was even more excited when his dad told them all three would be going to gardening day together. While there you brag how his mother saved the Grand Canyon, and then his dad offered to buy them all a sweet treat. That night his dad read him the book ‘Where the Red Fern Grows’ and his mom allowed them to continue camping. Even eventually joining them.("Grand Canyon")
Theo woke up early and wanted to surprise his parents by making banana pancakes. Apparently only just realizing he was nine years old, he gave up and tried to make cereal. But as parents caught him. The next day he was invited to a sleep-over for the first time ever. He was very excited and even packed his flashlight, telling his parents to go have dinner and fun with it. Unfortunately, he was so nervous and scared during the sleepover he couldn't eat and eventually called them to come and pick him up. ("Mixed Signals")
Theo is getting ready for school and insists his mom comes with them to drop a gift off for the baby. While there he sings to Charlotte and everyone else in the room before going to school. ("The Perfect Storm")
Theo is in bed listening to his mother read him a bedtime story. He gets upset when there are two dinosaurs from different time periods in the same photo. He demands someone look it up to confirm his suspicion, his dad does and agrees with him. Days later when his parents are again tucking him into bed, he asks if they are ever going to have another child, but they both confirmed they only want him. ("Austin")
Theo is surprised to find out his mother will be driving him to school instead of his dad. He's even more surprised to find out that his dad is watching baby Charlie when he thought his dad didn't like kids. His mom confirms he does, and is doing it to help out the family since Jonathan is dead. ("Unleashed")
Theo is ecstatic to be celebrating his 10th birthday. His parents have invited all of his friends and their friends and their friend's kids over for a grand party. Everyone sings to him while he was presented with a cake, Theo couldn't be happier. ("Ten Years")
|Father||Mother||Father †||Joo Hee Kim|
|Lindsay Saville||Eddie Saville||Katherine Saville||Tina Kim|
|Delilah Dixon||Theo Saville|
- Eddie and Katherine are divorced.
- Eddie and Delilah only had an affair, and have never been married.
- Initially, Theo's name was supposed to be "Caleb", but DJ Nash changed it because it is the name of one of his kids' friend.
- By the events of "Ten Years", Theo is 10 years old. By the events of "Piece of Cake", he is 12 years old.
- At first, it was stated that Theo was 7 years old in "Secrets and Lies", and that he turned 8 by the events of "The Rock". As these episodes take place in January and May/June 2019 respectively, it seemingly meant that Theo was born between these months in 2011.
- However, in "Mixed Signals", Theo states that he is 9 years old, making him a year older than what he is supposed to. This change means that Theo was born in the second half of 2009.
Gallery of photographic stills used to promote the character.
|A Million Little Things: Season 1|
|"Pilot":||"Band of Dads":||"Save the Date":||"Friday Night Dinner":||"The Game of Your Life":||"Unexpected":||"I Dare You":||"Fight or Flight":||"Perspective":|
|"Christmas Wishlist":||"Secrets and Lies":||"The Day Before...":||"Twelve Seconds":||"Someday":||"The Rock":||"The Rosary":||"Goodbye":|
|A Million Little Things: Season 2|
|"Coming Home":||"Grand Canyon":||"Mixed Signals":||"The Perfect Storm":||"Austin":||"Unleashed":||"Ten Years":||"Goodnight":||"Time Stands Still":||"The Kiss":|
|"We're the Howards":||"Guilty":||"Daisy":||"The Sleepover":||"The Lunch":||"Change of Plans":||"One Year Later":||"Mothers and Daughters":||"'Til Death Do Us Part":|
|A Million Little Things: Season 3|
|"Hit & Run":||"Writings On the Wall":||"Letting Go":||"The Talk":||"Non-essential":||"Miles Apart":||"Timing":||"The Price of Admission":||"The Lost Sheep":|
|"Trust Me":||"Redefine":||"Junior":||"Listen":||"United Front":||"Not Alone":||"No One Is to Blame":||"Justice: Part 1":||"Justice: Part 2":|
|A Million Little Things: Season 4|
|"Family First":||"Not the Plan":||"Game Night":||"Pinocchio":||"Crystal Clear":||"Six Months Later":||"Stay":||"The Things We Keep Inside":||"Any Way the Wind Blows":||"Surprise":|
|"Piece of Cake":||"Little White Lies":||"Fresh Start":||"School Ties":||"Fingers Crossed":||"Lesson Learned":||"60 Minutes":||"Slipping":||"Out of Hiding":||"Just in Case":|
- His name was originally Caleb, but we changed it because that’s the name of one of my kids’ friends., by DJ Nash, Twitter (October 21, 2019)
- I wanted Tristan to play his age so I made a jump. I’m a dad first. Good for you for catching it., by DJ Nash, Twitter (October 24, 2019)