Bot 13 (called Beep Boop by Wander) was a Dominator Probe sent by Lord Dominator to get a substance called Volcanium X, which she uses to supply her army, ship and weapons, to a planet with tons of it.
He was exactly as the other Dominator-probes.
When Bot 13 found the planet with tons of it, goes there, but hit Wander's kite, causing him to crash. Wander helped him, and he spotted Volcanium X at a carnival game, so he tried to get it, but couldn't, resulting in him staying damaged. Later, when both were sitting on a dock together, they were spotted by Sylvia, who was very upset when she found out Wander had won him the Volcanium. He flew back to Dominator's ship and showed her the planet. Dominator was very proud and asked for the coordinates, but he realized that Wander was right. He refused to show her the coordinates, and deleted the planet info, and Dominator was very upset. He was beaten up by Dominator, who sent him into space. While flying, he pulled out the pictures him and Wander took earlier, and disintingrated. His last words were, "I am Beep Boop." He were last seen when he appeared as a shooting star near the planet Wander and Sylvia were on. Wander and Beep Boop's pictures are then seen floating through space as proof of their friendship.
Meanwhile, Sylvia realizes that Dominator has not arrived to destroy the planet, understanding that Wander has indeed reformed Beep Boop. Wander watches a shooting star and wishes Beep Boop good luck, sadly unaware of his death.