It helps immensely to use these terms:

Sir Pentious, Helluva Boss, Hazbin Hotel, show style, snake angel, 1boy, solo, male, boy, guy, pectorals, flat chest, chest eye, snake hood, snake, serpent, visible fangs, top hat, yellow sclera, red pupils, tiny blue wings, slate blue skin, lavender tail, alice blue tail belly, small blue wings, yellow stripe suit, hat eye, halo, heart glasses, heart goggles, black bowtie with red heart, red claws,

If you want him without his hat on his head (worked hard to get the system to understand this),

Sir Pentious, Helluva Boss, Hazbin Hotel, show style, snake angel, 1boy, solo, male, boy, guy, pectorals, flat chest, (hat off), chest eye, snake hood, snake, serpent, visible fangs, yellow sclera, red pupils, tiny blue wings, slate blue skin, lavender tail, alice blue tail belly, small blue wings, yellow stripe suit, halo, black bowtie with red heart, red claws

Also, his hood. Here are some key phrases:

snake hood down, hair down (to have his snake hood down more like hair)

snake hood flared, hair flared (To have his snake hood flared open to be surprised, threatening, etc.)