I don't consider Gremlin to be very photogenic. He tends to be dusty and his black fur defeats auto focus most of the time. The trick seems to be to use long enough lenses (all photos here were done with 50mm and 100mm but 200mm would keep me outside of his area of interest). That allows getting low enough without getting his attention.
For light, I've mostly used bounced flash. Some low light source is also needed to add catchlights to the eyes. A couple of photos were done with studio lights, but those only work if he's interacting with a human.
Have to watch where he's looking and turn the flash head to light from that direction. I think that a soft front light and a hard backlight would do well to show forms and fur texture, we'll see how that idea works out this weekend.