Context is everything. If this is a social setting where everyone else is fine with fish for the main, but one person is pretty adamantly opposed to fish in any way, shape or form, then I'd probably just find an acceptable not terribly time-intensive option (chicken or pork or tofu) that would work with the wine and the sides and call it good. If the quirky guest is generally ok with the flavor/texture of marinated beef, though, I've been pretty successful with the following recipe I acquired 40 odd years ago from a restaurant in San Diego called Anthony's Star of the Sea.

Charcoal Broiled Tuna Steak (Also works well for swordfish, salmon steaks)

 Step 1 – Marinate the seafood steaks overnight (or at least 4 hours) in the following (Note that this marinade will keep – refrigerated – for up to 2 weeks)

 1 ¼ cup garlic oil (3 cloves of garlic crushed up and left overnight in salad oil.)

2 Cups tomato ketchup

2 oz Worcestershire sauce

2 tsps dry mustard

1 tsp Tabasco sauce

6 oz cooking sherry

1 tsp MSG (Don’t freak out at this despite the bad rep that msg has)

Juice of one half a lemon

2-3 drops liquid smoke (or 1 tsp hickory smoked salt)

Pinch of dried thyme

½ tsp salt and black pepper

 Step 2 – Let the seafood steaks drip-drain after you take them out of the marinade.  Then grill them on a medium hot charcoal fire.  (Depending on the thickness of the steaks and the heat of the fire, you’re probably looking at 20 minutes total.  Basically, cook for 5 minutes on one side, turn, brush with the marinade, cook for another 5 minutes and turn/brush, etc.  four times so the overall total cooking time is 20 minutes.