Dennis

Dennis is a Warrior (Light) and one of the people spawned in the Tutorial along with Jake,

Dennis and Lina are mentioned as energetic twin cousins always arguing pointlessly,

Story Summary
Dennis, Lina and their colleagues ; Jake, Jacob, Bertram, Caroline, Casper, Ahmed, Theodore and Joanna spawned in the Tutorial together, He and his group joined Richard after Jake left, They were separated by Richard into other hunting group,

Jacob mentioned Dennis and Lina were ambushed by Hayden's members during negotiations with said group, But they claimed it was not them so it could most probably be William's deed, This occurred even before Jake made out of his Challenge Dungeon,

Alternate Events if Jake's Bloodline did not exist
The Malefic Viper mentioned that Dennis, Lina and Jake would die on their first night's watch in the Tutorial if not for Jake's Bloodline anomaly,