Calculus is the only main character in the Tintin series to display signs of attraction to women. This is notably evident in his interactions with Bianca Castafiore, with whom he is smitten during her long stay at Marlinspike Hall in The Castafiore Emerald. During her stay, his botanic experiments lead him to create a new variety of rose, which he names in her honour. Nonetheless, he happily congratulates Captain Haddock on his "engagement" to Castafiore (in fact a media hoax which he unwittingly fuelled).