La'gaan and M'gann met on September 6, 2010, before she had truly begun a relationship with Superboy. They struck up a relationship shortly after M'gann's relationship with Superboy ended. M'gann felt La'gaan made her happy with herself.
La'gaan was uncomfortable with his "impure" appearance, and the way it sidelined him for most missions. Early on, M'gann comforted him by showing him her true appearance, though he was not frightened by it.
In the early stages of the relationship, Lagoon Boy became jealous every time M'gann's past relationship with Superboy came up, or if she showed concern for her former boyfriend. He also did not like it when the two former lovers were alone together. Superboy did not like the relationship, or Lagoon Boy. He thought he was a jerk, though he did think he treats M'gann right.
They were quite open with their relationship, unlike with Superboy at first, and often hugged or made out in front of everyone. Despite his appearance, they figured out a way to go on dates together.
After Miss Martian mindblasted Aqualad and learned that he was not responsible for killing Artemis, she became increasingly drawn back. She ignored several of La'gaan's messages, but did spend time with Superboy, which made La'gaan jealous. Before he could press the issues, Miss Martian was kidnapped by the Light.
During the seven weeks she was kept aboard the Manta-Sub, M'gann had time to think things over. She realized La'gaan would only ever be a rebound guy to her. After she escaped, she told him she considered the relationship over. He did not take that well, and tried to mend it. He expressed the hope their love could grow, but M'gann could not see it. La'gaan suspected she still had feelings for Superboy, but Miss Martian denied it was Conner's fault, or La'gaan's. She only blamed herself, and felt he deserved better.