Hagens was born in Hauppauge, New York and has played for the USNTDP since the 2022 season when he scored 26 goals and 40 assists in 43 games for the US National U17 team. This was only a part of what Hagens accomplished in 2022-2023. He also played for the USNTDP Juniors in the USHL and tallied 17 goals and 23 assists in 31 games. He was not finished yet and played Internationally for the US National U18 team, the USA U-17 and U-18 squads in the WHC-17 and WJC-18 respectively. His totals combined for those three teams were 31 games played for 16 goals and 29 assists.
After playing a combined 105 games as a 16 year old in 2022-2023, Hagens netted appreciable numbers for three different teams in 2023-2024, cementing himself as one of the top prospects in the 2025 class. He scored 39 goals and 63 assists in 58 games for the U.S. National U-18 team (USNTDP) and for the USNTDP Juniors team in the USHL he tallied another 18 goals and 29 assists in 26 games. He capped off his successful season by playing for the USA U-18 squad during the WJC-18 Championships, and scoring nine goals and 13 assists in only seven games.
After the 2023-2024 season, Hagens announced that he was going to follow the paths of some recent prospects and play NCAA hockey, committing to Boston College for the 2024-2025 season.