How does the brook behave when it encounters curves on its banks?

Tennyson's poem "The Brook" is written from the perspective of an indefatigable brook which goes on "for ever" regardless of what it encounters on its travels. The speaker, the personified brook, states in the poem that "with many a curve my banks I fret." The subject-object construction of this sentence does not posit that the brook encounters curves on its banks, as such. Rather, the brook says that it frets its banks with curves, a representation of the fact that it is the brook itself which is carving out these curves in its banks over a long period of time. Because it rigorously and continuously follows its own desired path relentlessly, the path of the brook will eventually shape the landscape through which it travels.
Eventually, at the end of its journey, the brook will "curve and flow" outward to meet the sea. However, while this is the end of its journey in a geographical sense, the brook itself will continue to flow from its source toward its mouth at the sea, regardless of the behavior of those who watch the brook pass. It is endless, infinite, and capable of making a permanent mark upon the land through which it travels, curves and all.