Dennis joined The Dons on loan from Bundesliga side Hoffenheim in February 2026. Geiger has spent more than 16 years with Hoffenheim, having joined the club in 2009 and progressed through their Academy before making his first-team debut in a 1-0 Bundesliga victory over Werder Bremen in August 2017. Four days later, he made his UEFA Champions League debut away to Liverpool FC at Anfield. Geiger has gone on to make close to 150 appearances for Hoffenheim across domestic and European competitions, becoming a regular presence in the Bundesliga over the past six seasons.