Illustrious:

For apperance add: "knight \(hollow knight\), blue cape"

Pony XL:

For apperance add: "1other, knight_\(hollow_knight)\, horns, black skin, mask, hollow eyes, blue cloak"

Recommended strength: 0.8~1.0

For negative prompt it's recommended to add "(ears:1.35), sword, mouth, blush"