Flustered, uncomfortable, and guilty pleasure
Lud gets flustered when he’s crushing on someone and someone confronts him about his feelings. As for Francis, he gets flustered when he’s being hit on (since he’s so used to hitting on people).
Francis gets uncomfortable when people try to force him into situations he doesn’t want fo be part of. Same for Ludwig, and hes also not comfortable with being touched (unless it’s by his SO).
Lud’s guilty pleasure is eating sweets. He loves em. Francis’ is his tendency to collect little souvenirs from the places he visits, no matter how overpriced they are.