Wilson couldn't believe what he had found out. House had brain cancer, and he didn't tell him. He had gone to Kupersmith instead, yeah, Kupersmith is excellent in his field, and Wilson himself would've recommended him, but House was his best friend. He shouldn't have had to find out from an upset Cuddy, asking him questions about an oncologist's specialty.
Then, when he confronted House, House said it was nothing. "It's nothing." Muttered Wilson, dejectedly, as he opened the door to his office, "It's nothing to hear that you're best friend is dying from your boss, it's nothing to know that he didn't come to you first." He closed the door behind him, and sat at his desk. He bit his lip, preventing himself from screaming. It might be nothing to House, but it was everything to Wilson. He had nearly lost him twice, once with the infarction, and a second time with the shooting. Brain cancer symptoms started showing slowly, and Wilson didn't want to think about how much it would hurt to see his friend die. Why House? Wilson did not want to watch him slip away. It was nothing to House but without House Wilson had nothing.
