The character's age can only be guessed at based on his brother Joe's accounts and Slade's own history, the latter tells us that:
- 2004: Grant doesn't exist yet, and this was the year when a teenage Joe sees his father killing someone for the first time.
- 2006: Grant wasn't born yet, or his father (who had a lot of Intelligence resources, and special skills on his side) somehow didn't know of his existence. Adeline Wilson could be pregnant by the time Slade goes to Lian Yu where he gets stuck for a long time.
- 2019: Grant should never be older than 15 years old.(Ollielover (talk) 09:52, November 8, 2019 (UTC)).
Seems to be a continuity error. Grant would have been born either in 2006 after Slade went on a mission for ASIS with Billy to rescue Yao Fei or in 2012 after Slade left to get revenge on Oliver. Either way, he should not already be an adult by 2019.Ninja72 (talk) 12:22, November 9, 2019 (UTC)