Firus previously competed with Caelen Dalmer and Lauren Collins in the junior and senior ranks.

[4][5] Dalmer/Firus were coached by Rod Mackie and Shae Zukiwsky before joining Megan Wing and Aaron Lowe in Burnaby, British Columbia.

[2] They decided to train at the Mariposa School of Skating in Barrie, Ontario, coached by David Islam, Kelly Johnson and James Callan.

After moving up to the senior level, they placed fifth at the 2015 CS Nebelhorn Trophy and tenth at the 2016 Canadian Championships.

[14] Following the 2018 Winter Olympics, Tessa Virtue and Scott Moir withdrew from Canada's delegation to the 2018 World Championships in Milan.

[15] At their second Challenger event, the 2018 CS Finlandia Trophy, they finished fourth overall, having placed third in the rhythm dance and fifth in the free skate following an error from Soucisse on the one-foot step sequence in the latter.

[16] The duo had two Grand Prix events for the season, beginning with the 2018 Skate Canada International, where a fall on the midline step left them in ninth place after the rhythm dance.

[17] Following the Grand Prix, the two opted to return to their previous season's free dance, as the Weeknd medley they had been using had not received the scores they would have wanted.

[18] The free dance proved difficult, with Soucisse struggling on her twizzles and falling toward the end of the program.

[23] Early in the free dance, Firus fell on the one-foot step sequence, and they finished third in that segment as well, winning the bronze medal.

Shortly afterward, the World Championships were cancelled due to the COVID-19 pandemic, which they later called "a big low" for them.

On April 16, 2020, Soucisse/Firus announced that they would be moving to train at the Scarboro Figure Skating Club under Carol and Jon Lane and Juris Razgulajevs.

[27] Due to a minor training injury, they were unable to participate in filming for the virtual 2021 Skate Canada Challenge and were granted a bye to the 2021 Canadian Championships.

[35] They were eleventh at the 2021 CS Finlandia Trophy after a rhythm dance error left them in fourteenth place after that segment.

[12] They were initially assigned to the 2021 Cup of China as their second Grand Prix, but following its cancellation they were reassigned to the 2021 Gran Premio d'Italia.

Following their release from Skate Canada, Soucisse/Firus made their international debut for Ireland at the 2023 Bosphorus Cup where they came eighth.