What could he be?

Size and general shape make me think of a lacy too. Maybe lacy/curdog blend?

a lacy is a curdog.
most cur breeds come in brindle

I mean, lacy with some other curdog, as they don't come in brindle and the ears on the op's dog aren't as houndy as most lacys. I thought lacys had a good dose of hound in them too?

Maybe I'm wrong since I haven't seen tons curs in person, but I also got the impression lacys are smaller sizewise than other cur types.

lacys & alot of mt curs are pretty small 30-50#. as a performance breed traits that don't affect performance are highly variable so some ears are long & some aren't.

Meg is supposed to be pure Mountain Cur, and is 36 lbs and about 18". I'd guess that the other dog is right around there as well, although it is hard to tell from pictures of course.

Thanks! That makes a lot of sense.