Blists feels the emotions of its Trainer while it sleeps, so it makes sure to give them one of their eggs during dinnertime, as they are laced in happiness: it is impossible not to grin after taking a bite, just like Blissey's eggs.
A Blists has the power to sense the emotions of people and Pokémon with the horns on its head. If it senses sadness with its fluffy fur, a Blists will rush over to the sad person, however far away, to share an egg of happiness that brings a smile to any face.