Batman and Ra’s al Ghul’s daughter Talia had a long standing on-again/off-again romance. A story would eventually emerge where the couple bore a son but Talia, fearing Batman’s protective nature would get him killed, claimed she miscarried and put the child up for adoption. Following the events of Infinite Crisis, the story was altered in that Batman is unaware he has a child as the boy was created artificially from Batman and Talia’s DNA. Named Damian, the child was raised by the League of Assassins to be a killer with few parallel. Hearing stories about his father over the years, Talia offloads her offspring onto Batman to disrupt his work as his son eagerly wants to impress him. However, Damian developed a murderous jealousy with Tim Drake, Batman’s current Robin, and executes one of Batman’s enemies. Damian would adopt a Robin costume but wouldn’t officially be recognized as inheriting the mantle until the seeming death of Batman where Dick Grayson takes on his mentor’s identity and fires Tim Drake (who then becomes Red Robin). Damian would remain as Robin for a while, including when his father would return, until his mother put a price on his head leading to Batman faking his death. Damian would adopt the role of Redbird until he was killed by his clone the Heretic. Later, Batman would use an artifact called the Chaos Shard to resurrect Damian who again became his Robin. Following the events of DC Rebirth, Damian became the leader of the Teen Titans. For Young Justice, Batman and Talia were shown to be lovers in 2009 before he broke it off with her over her devotion to her father.
Honorable mentions: Koryak, Connor Hawke, Jemm: Son of Saturn, Cassandra Cain, Lor-Zod/Chris Kent, Scandal Savage, Lena Luthor, Nyssa Raatko, Ravager, and Harley Quinn.