This is a bounty entry. Previously known in the fan translation as "Sebastian Debeste." Because he's Debeste.
Weight: 1.0
Trigger + Appearance: eustace w1nner, flipped hair, ahoge
Default Outfit: school uniform, red jacket, jacket on shoulders, blue jacket, badge, long sleeves, white shirt, white gloves, blue pants
Add brown hair and brown eyes if necessary.
The results of your generations are dependent on the additional LoRAs, weights, and models you use, so it may not work or come out as consistent as my sample images.