Lexaeus did not like to waste words, nor did he waste emotions. When Lex spoke, it was so rare that everyone listened, and when he felt strongly, it was blatantly obvious. So, when Lex fell for a scrawny nobody named Zexion, everyone knew about it.
Lexaeus preferred to speak through actions, rather than words. To tell Zexion that he fancied him, he began to play the gentlemen. He opened doors for Zexion, usually ripping them off their hinges in a bashful, embarrassingly eager way. He stood up for Zexion when he was being bullied, much to the dismay of Axel's nose, which was quickly broken.
It didn't take long to catch his meaning. Zexion told Lexaeus that he fancied him back, by kissing him in the hallway. Lex told Zexion that he was grateful by fucking him against the wall.
Their relationship was a strange one. For one thing, they didn't talk. Sometimes, when one of them was away on a mission, they would "talk" on the telephone. They usually just listened to each-other breathe. Their time together was defined by comfortable silences, whimpers, grunts and moans.
Lexaeus did not like to waste words, nor did he waste emotions. So, when he said "I love you," Zexion knew that he meant it.