Ludo is the embodification of gentle giant. Our first glimpse of him is his ferocious bellowing, which scares away Hoggle. Expecting a vicious animal, we first meet him in a doubly-submissive form – upside down and being nibbled by beasts on sticks.
For whatever reason, Ludo can control the rocks with his voice (“Sure, rocks friends”). I don’t know what’s up with that. Ludo is an anagram for loud, so I guess that’s something.
Ludo speaks in a simplistic, childlike way: “Sarah friend” “Ludo down” etc.
Despite being cute as all heck, Ludo unfortunately lacks the detailed characterization of the other puppets. But he does get a lot of mileage out of his supermobile eyebows.