I soften the letters and lines on a page.

BLINDNESS

Explanation:

• "I soften the letters and lines on a page,"

When someone goes blind or experiences vision loss, their ability to clearly see and write diminishes, often making their handwriting appear softer or less distinct.

• "They say I am brought on by love, old age, diseases, genetics, and freak accidents,"

Blindness can result from various factors such as aging, hereditary conditions, illnesses (like glaucoma or cataracts), or accidents that damage the eyes or optic nerves.

• "With darkness, I grow more intense."

Blindness is, by definition, the inability to see, which becomes more pronounced in the absence of light or in dark environments.