Shrievers are as intelligent as humans and can easily learn foreign languages. The majority of them are mean and hated by all inhabitants of Lugubria. As they are adaptable and fast mutating creatures, they can survive in all landscapes and can have all conceivable characteristics. Some have additional arms, others can breathe fire or have mustaches!
They'll creatively assist you in dying
They have also mastered speaking human languages. Shrievers, like most Luridian dragons, are allergic to citrus, and detest it.
The shriever breeding program, building a better shriever - and by "better" we mostly mean "less impossibly vicious and stubborn"