Disclaimer: not mine, sadly
Simon understood what it was to feel used, to feel left alone and abandoned. To not understand why the world was crumbling around your feet, why the earth was shattering and your ears were ringing. He'd felt it the day they took his sister away…like he knew what was happening, like he knew straight away the men were not to be trusted, shouldn't be allowed to take his baby sister away from him. She was eight back then.
He knew, also, what it felt like to be blamed, to be the only person in a world of fools to understand what was really going on. He'd felt it all the while as he'd searched for River, day after day of struggles, of climbing over obstacles that no one else could see.
But more than that he knew how it felt to sacrifice everything, everything, just to save someone you love. To give up every chance, every hope or dream you ever had, just to get them back. After all, what else but that had he done in his search and release of River. He'd given up his career, his future, his friends and god! even his family, just to get to her. Because she'd needed him.
No one in the 'verse had understood that but him till he'd boarded this ship. Because he was increasingly becoming aware that the Captain had been doing nothing but that ever since the war. And now he was putting what little he had on the line, just for him? For a belief in what was right? It didn't seem possible, but Simon knew instinctively that that was what it was. And he was more grateful than anyone knew.
Because, even while the world was crumbling, as people were suffering, just to protect him, Simon knew exactly what Malcolm Reynolds was going through. Because he'd gone through it himself, a thousand times over.
And he'd do it again, in a heartbeat. Because River needed him. And there was nothing in the 'verse that would stop him from protecting her. Not this time.