Finn was 12 when the series started on 5 April 2010; had his 13th birthday in "Mystery Train" (14 March 2011, middle of Season 2); and turned 14 when he met Flame Princess (13 February 2012 was the Season 3 cliffhanger, which was resolved when Season 4 began on 2 April). He's maturing at the same pace as his voice…

Finn was 12 when the series started on 5 April 2010; had his 13th birthday in "Mystery Train" (14 March 2011, middle of Season 2); and turned 14 when he met Flame Princess (13 February 2012 was the Season 3 cliffhanger, which was resolved when Season 4 began on 2 April). He's maturing at the same pace as his voice…

That's the gorgeous Jessica DiCicco as the voice of Flame Princess.