Alexander is the youngest of the triplets and the most troublesome. He often teases Flora and even likes to watch storms scare her, despite all this, he has her back. He often plays with his older brother, and usually drags his siblings into a little trouble like when he piloted an airplane and got into a hot air balloon without realizing a storm was coming. He was the first one of his siblings who tried to play with his newborn sister Isabelle. In later episodes he has shown to not want to be around her, by the end of the episode, he warms up to her. He is also a thrill seeker, often wanting to do things that most children his age would not be able to or want to do, such as riding a Ferris wheel or riding in a balloon. In Oh To Be An Adult, he is the first of the triplets to decide that he is old enough to make his own decisions. He is the most athletic of the triplets as he plays soccer, tennis, basketball and is a rower. He also enjoys reading comic books including the Scarlet Pachyderm, he even gets excited when Uncle Arthur dresses up as the Scarlet Pachyderm, even though it did scare his little sister.
He can be a show off sometimes, when Pom was trying to practice for the basketball tryouts Alexander would twirl the ball and shoot impossible shots, but was willing to help his brother out, especially when Pom was made towel boy. He can at times be a little selfish, such as the time he wanted to be King even though his parents wouldn't allow it, and his siblings thought that was ridiculous. He manages to sneak onto a plane and when he ended up starting it he still pressed the wrong one which landed him into uncharted jungle. He thought they were in a big park but Arthur told them that these parts of the jungle are uncharted and could be dangerous. While trying to make a balloon, Alexander tries to find food instead of helping them fix up a balloon. He goes to get tree sap but is getting fed up with his brother and sister ordering him around, even though they are in the right. Alexander is eventually captured by a tribe and made their King, while he enjoys it, especially since he gets to order his siblings around, they soon learn the tribe actually wants to cook Alexander and they soon escape thanks to Arthur. Alexander apologizes for his behavior and the two forgive him. While he can be self centered, he still cares very much about his siblings, when Flora was bitten by a poisonous snake, he refused to rest and even crossed the gorge to the "Witches'" house to heal her. He is also very good at noticing something that no one else does at first, such as a time traveler, a witch and a sea serpent.
- Alexander is absent from Babar and the Adventures of Badou, it's unknown where he is, but he's officially an uncle and very possibly a father as well.
- The differences between him and Pom is his outfit. Alexander wears a t shirt with blue lined sleeves rather than a collared shirt and has blue shoes.
- In Season 3 he began to be voiced by Stuart Stone, who was the voice of Young Arthur.
- Unlike his brother, Alexander wears footie pajamas instead of shirt and pants combo.
- In the earlier seasons, he does jump to crazy conclusions, such as believing that monsters are real even after he is told there is no such thing as monsters.