A-M[]
A, B and C[]
A, B and C seem to be really close with each other. A and B even have a band along with B's brother D and their friend N.
A and E[]
E and A have been shown to be great friends. In Sleep, when A fell into E’s bed, they both said “what a treat!” Indicating that they both enjoy each other's company. Additionally, they say “we make a world-class T-EA-M!”, indicating that they complement each other well when together. They have also been shown to be rather playful together, as seen in the scene in sleep when they ran around each other in circles. In Lips, when A woke up from her “nap” she immediately went to E and started jumping around with him enthusiastically. In Name, A said that E and her could “play a little game”, further showcasing this playfulness.
E appears to care deeply about A. In Name, when A first had the hiccups, he said it was an “emergency”. At the end of the day, E was the one who helped A say her name. E also comforted A after she fell down in The Case of the Missing Blocks.
Occasionally, E and A seem to be somewhat in sync, as seen in Making Friends and Name, when they posed together at the same time. This is likely the reason why they make such a good team. Also in Making Friends, during the song remix, A was singing with the BAND, but let E sing into the microphone as well.
B and D[]
B and D are twin siblings who love music and playing their instruments. B has a bass guitar while D has drumsticks and a drumset. They usually love each other a lot but one day they had tempo trouble in the middle of a show so B tried to play D's drums but ended up breaking his drumstick! Naturally D was upset and left the stage heartbroken leaving B to save the show on her own. However nothing was right but luckily D could see she had trouble and once he felt a little better decided to come back! As for his broken drumsticks he had a large supply anyway! And together they managed to put on an amazing show!
C and K[]
C and K are siblings. Sometimes C doesn't like it that they make the same sound as shown in two episodes. The first was key when it annoyed her and she tried to stop him but agreed to share it in the end. the other case was when she was sad about it in clap and it made her feel unimportant but all it took to cheer her up was the encouragement of S and T and soon everyone was dancing together. One time she also ruined her brother's football when she tried to kick it. No matter what thought C and K love each other a lot and always end up having fun in the end like in kick when they played football against each other and then on the same team against a living sock.
M and N[]
N is on an endless mission to stop M from eating everything he sees. This happened in three episodes... in Snowman where he was eating snowflakes, in Man where he got his hands on A's apples and in On where he broke a piece of the screen and tried to eat it.
N-Z[]
J and V[]
J and V don't interact very often but they are very good friends in Van where V and A are on a mission to help J's wish to fly come true. The mission was V's idea and when J was about to give up he sung... "I don't know how I'm gonna do it. But I can do it if i try! I'm gonna find a way for J to fly!" also when J got a jet to help her fly in the end they raced each other and when the jet flew away into the sunset V waved goodbye to it.
Q and U[]
Q has a well known obsession with U much to his dismay. As a result he often runs away from her like he did in Alphablocks, Race and tried to do a few times in Quick. However despite his dislike for Q there were two episodes where he was actually comfortable around her. In Quick it looked like he was actually having fun playing piano for her until it got too fast. In Quiet he started the episode avoiding her as usual but in the end realised he needed her help.
W and X[]
In the intro X flies into the box with W and his best friend Y. He also gives them a ride to the finish line in Race. As seen in Web X is W's idol. He tried to be a superhero like him but didn't succeed until the end where it was X who was in trouble and W saved him and X praised him for his efforts.
W and Y[]
Y and W are often seen together and are best friends.
X, Y and Z[]
Mixed[]
A, B, D, and N[]
The BAND… well… have a band. B plays the bass guitar, her best friend A is the lead singer, their friend N plays the guitar and B's brother D plays the drums. They appear in "Sing", "Four", "Band", and are even the protagonists in the special "Band Together".
F, P, S, and X[]
All of them can fly. F, S and X were painting and flying together in Dots, while in Taps, P tried to cheer up S when she had a sad day.
S, T and R[]
S, T and R share many endearing scenes. R and S dance together in On, while in Why, R and T comfort Y and help him make his wish to join the vowels come true. In Taps, S has a sad day and T was trying to cheer her up. And in Clap, when she was jealous of X's powers and V's super-speed, T comforted her again and helped her realise she was special as she was!
With the Numberblocks[]
A and One[]
Yup, this is where it started. In Making Friends, A was accidentally sent up into the air until she reached space. Coincidentally, One was just flying by while exploring space. They said hello to each other before A dropped back down. One was excited to make a new friend so she landed with her magic mirror. The Alphablocks kindly welcomed her to the planet.
I and Three[]
I was at first not very happy about the visitors even to the point that she and Three started a rivalry. However, when I was sad and Three comforted her, they slowly became friends and even danced together near the end of the episode.
K and Eleven[]
K and Eleven both love football, so naturally they instantly became friends after they met and were seen playing football together.
X and Eight[]
X and Eight are both superheroes. One day, when Octonaughty was causing trouble in Alphaland, X was stranded in Numberland where he and Eight joined forces for the very first time and became good friends.
X and Twenty-Seven[]
At the end of Crossover, they gave each other a high five while X said "Excellent work, cube crusader!"