Fourteen year-old Leo is the son of former Wimbledon forward Stewart Castledine who played for the Dons between 1991 and 2000.
The teenager started off his career in the Wimbledon youth ranks at the age of seven, playing as a "tough-tackling centre-back".
But coaches spotted his potential immediately and thrust him into a more advanced role - either in the heart of midfield or as a No10, much like Mount.
On the transition Leo told BBC Sport: "Moving from defence to midfield was a very gradual process for me... It took about two seasons.
"I was a tough-tackling centre-back at the start of my Under-13 season.
"Now, towards the end of U15 season, I am a centre midfielder and sometimes play as a No10."