Oh! He's just adorable! So glad you finally found a bun to love. Do you know how old he is?
Do you have any favorite movies or books? You can use character names from those.
There are also lots of different theme groupings. (the following are for male and female, so you'll have to sort through). I underlined some I thought could work.
You could consider PLANT names like Basil, Pepper, Pumpkin, Rose, Daisy, Ivy, Lily.
Or "SKY" names like Orion, Pluto, Neptune, Draco, Galaxy, Nebula, Venus, Galaxy.
Or ROCK names like Quartz, Malachite, Copper, Clay, Diamond, Silver, Marble, Slate, Coal.
Or WEATHER names like Blizzard, Volcano, Storm, Dusty, Sunny, Cloud, Rain, Frost
Or based on COLOR ... in his case Midnight, Shadow,
Food names can be in themes as well…
COFFEE: Latte, Mocha, Coffee, Cocoa, Chino (short for Cappachino), Cream, Sugar
CANDY: Snickers, Twix, Skittles, Hershey, M&M, Pez, Toffee
MEXICAN: Burrito, Taco, Bean, Salsa
SNACKS: Popcorn, Peanut, Cheesecake, Cupcake, Cookie, Yogurt, Crumble, Dorito, Frito
SPICES: Cinnamon, Basil, Honey, Ginger, Garlic, Nutmeg, Mint
ICE-CREAM: Vanilla, Rocky Road, Cookie Dough, Chip, Strawberry
FRUIT: Peaches, Cherry, Raspberry, Kiwi, Blueberry, Tangerine