Keeping his little sister with him wherever he goes
The stack of bills is folded in half, which might not be immediately apparent. The original poster added some background to help clarify things. That bent, barely-recognizable piece of paper is an ultrasound — it’s hers. It was discovered in her late brother’s wallet along with a worn little poem, which had been carelessly ripped from its page.

She discovered it on the second anniversary of his death after she and her family had mustered the willpower to go through his belongings. Whatever their connection was, we can’t imagine what finding it was like for her. It must have been uplifting and devastating in equal measure to see genuine physical evidence of his love for her.