Answer
Geta's assassin was his younger brother Caracalla. Caracalla desired sole rule of the Roman Empire, which he shared with Geta following their father Septimius Severus's death in 211 AD. Seeing Geta as a threat, Caracalla plotted to eliminate him. In February 212 AD, Caracalla lured Geta to his mother's apartments under the pretext of reconciliation, where he had him killed by centurions of the Praetorian Guard.