Ademar is a character that appears in For Honor's single player campaign.
Ademar was Holden Cross' second in command first seen during the first mission of The Knights campaign, Warlords and Cowards. When Hervis Daubeny refused to duel Cross, Cross suggested that he fight Ademar as his second instead. Daubeny selected The Warden as his second for the duel, prompting a duel between them.
The Warden acknowledges Ademar's skills in combat, thinking that he might have been a Warden before joining the Blackstone Legion. However, he was still defeated and killed by The Warden.
Nothing is really known about Ademar, as he only speaks during the beginning of the mission when he relays Cross's orders to the soldiers to "break it [Daubeny's fortress] down". It can be presumed that he is loyal to Cross, as Cross has him as a second.