Wim has dark hair which he keeps cut in a crew cut. His civilian clothes consist of a long-sleeved shirt and long pants.
Like the rest of the Jaegerists, Wim seems to be a man possessing extreme radical tendencies. He is among the Scout soldiers who openly rejoice at having launched a successful attack on Marley, despite the casualties they suffered in the process and feels no qualms about leaking military information to the public or defecting from the military altogether.
Wim participates in the Scout Regiment's raid on Liberio in the year 854. As the Scouts retreat from the battle Holger joins his comrades in celebrating their overwhelming victory against Marley. Their celebrations are interrupted by a girl boarding the airship and shooting Sasha Braus, prompting Wim and the others to beat her and her companion mercilessly.
Following Eren Jaeger's arrest for disobeying orders, Wim is among the soldiers who leak the news of Eren's detainment to the press to pressure the military into releasing him. After they are caught, the perpetrators are all arrested and Hange Zoë says they will be prosecuted.
The rebels are freed from their cells by guards who have also sided with Eren and rendezvous with Eren himself outside of the city. Eren declares that their next objective will be to find and team up with Zeke.
The group receives word from a Marleyan that Hange has arrived at the restaurant he is working at and storm the restaurant to capture her and the other Scout officers that are with her. When Hange refuses to tell them where Zeke is, they take all of the officers captive. While en route to Shiganshina, Wim and Hange notice Falco Grice reacting to Zeke Jaeger's scream.