Some guests are polite and work with the host house to keep the house in order and running well(Mutualism). Some guest come in have a wild party reproduce like crazy and then break the walls down on the way out(HIV). There are many types of houses and many types of guest as indicated by the linked wiki article.
METAMIA is a free database of analogy and metaphor. Anyone can contribute or search. The subject matter can be anything. Science is popular, but poetry is encouraged. The goal is to integrate our fluid muses with the stark literalism of a relational database. Metamia is like a girdle for your muses, a cognitive girdle.