2009-10: Brassard appeared in one midget AAA game for the Gatineau L'Intrepide, spending the bulk of the season playing in lower levels of midget hockey in his hometown. He did not allow a goal in his only appearance with L'Intrepide.
2010-11: Brassard was acquired by the Lac Saint-Louis Lions in a special draft for players released from their local clubs and had a successful season as the Lions reached the Telus Cup (Canadian midget championship). In 28 regular season games he was 23-3 with two shutouts and had a 2.47 goals against and .918 save percentage. After finishing first in the Reebok Division, the Lions rolled through the playoffs and defeated College Notre-Dame in the finals to reach the Telus Cup. Brassard won a team record 13 playoff games; with a 2.63 goals against. In seven games at the Telus Cup he was 4-3 with a 2.85 goals against and .900 save percentage. Lac Saint-Louis defeated the Vancouver NW Giants in the bronze medal game. Brassard was selected by the Quebec Remparts in the sixth round (92nd overall) of the 2011 QMJHL Entry Draft.
2011-12: Brassard appeared in 37 games for Quebec in his first QMJHL season. Working in a tandem with Phoenix prospect Louis Dominque, Brassard was 20-13 with two shutouts and had a 2.80 goals against and .905 save percentage. The Remparts finished third in the East Division and reached the second round of the playoffs. Brassard did not see any action in the playoffs as Dominque started all 11 games. Ranked 15th amongst North American goalies in Central Scouting's final rankings prior to the 2012 NHL Draft, Brassard was selected by Ottawa in the sixth round (166th overall).
After a rookie season in junior that saw him challenge his 19-year-old teammate for the starting duties, Brassard served notice that he has the talent to succeed. Unflappable between the pipes, Brassard is equally focused on improving his play both on and off the ice. A project, Brassard needs to continue to improve all aspects of his game, notably filling out his 6'1 frame and strengthening his puck moving ability. Although raw, he has the talent to surprise.