Septimius Severus' son Geta was killed by his elder brother Caracalla, who thus became sole emperor.
Citation:
Bouchard, Elsa. "Murder of Geta".
The Literary Encyclopedia. First published 01 March 2010
[http://www.litencyc.com/php/stopics.php?rec=true&UID=11496, accessed 23 May 2013.]