[His struggle to suppress his laugh only confuses her more, and for a moment she looks pretty irate - but then, her frown smooths out. She'll be composed! She knows her principles; nothing can shake them.]

You have it the wrong way around. Us mutually helping each other doesn't mean that our relationship is transactional; it means that we both extended kindness to each other.

[The result may be the same, but the principles behind it matter!]

The sea and the land can both be hard to live in, and it's important to keep a balance in the nature we occupy so that we don't deplete it for ourselves, but they are our environment, not the people within.