Ok but imagine that Chris get sick right, really sick, and he needs like a kidney or a liver and Eddie gets tested but he isn't a match and it's killing him, because what do you mean he isn't a match that's his baby, he's half his DNA why isn't he a match? Eddie is losing his mind, and Chris is sicker than he's ever been and there's nothing, nothing Eddie can do. They get Chris on a transplant list, but the chances of him getting an organ before it's too late are slim.
Buck gets tested too obviously, before Eddie can even ask, because that's his kid also no matter what labels they put on it, and seeing Chris' pale face and small body hooked up to all those machines makes him sick to his stomach. He's facing the possibility that his kid, his little superman, might die, and he's not sure that a world without Chris is one he can exist in. He knows it's one Eddie definitely cant.
They tell the 118 and they all immediately decide to get tested too, but none of them are a match either, and they can see Buck and Eddie dissolving before their eyes, Eddie is frantic and catatonic by turns, Buck can hardly stop crying long enough to eat.
Maddie sees this, sees her brother's despair and Eddie falling apart and the preumptive grief that is hanging over the 118 as Buck and Eddie spend almost every second at Chris' bedside. No one asked her to get tested. She thinks maybe they just forgot.
She doesn't tell Buck what she's doing. He and Eddie have had their hopes dashed too many times already, and if she isn't a match it won't matter anyway. She just goes to the hospital and quietly asks to see if she could be a kidney donor for a patient there, one Christopher Diaz. They take a few vials of blood and do some scans. After a while the doctor comes in and miracle of miracles, tells Maddie she's a match.
The doctor asks when she'd be available for surgery, citing the need for Chris to get the kidney as soon as possible, and Maddie doesn't even hesitate. Chim's with the kids at his parent's house tonight, she doesn't work until the weekend, and this is for Buck's kid. She asks if they can do it right then.
One of the surgeons agrees to stay overtime an the next thing she knows she's in a cap and gown being wheeled into the OR. She asks if she can be put in Chris' room when she wakes up and the doctors agree provided Chris' guardian consents. Somehow, Maddie doesn't think Eddie will mind.
Not that he or Buck knows she's doing this. She'd made it very clear she wanted to remain anonymous until after the surgery was done and Chris had his new kidney safely in his abdomen.
To her surprise when she wakes up Eddie is the first face she sees, camped out by her beside, but when she turns her head she can make out Chris' curly head on the other side of the room, Buck holding his hand as he sleeps.
To Maddie's absolute shock and horror the second Eddie notices she's awake he bursts into tears, crying and thanking her over and over for saving his son and how he can never repay her for this as long as he lives.
And Maddie just laughs and waits for him to calm down, smile going soft as she takes in Chris' still sleeping form, his face somehow already looking healthier.
"Anything for my favourite nephew."
Eddie smiles, and Buck goes bright red where he's totally eavesdropping on the other side of the room, but neither of them deny it.
Maddie gets best aunt privileges for the rest of time and Eddie buys her ridiculously expensive Christmas presents every year forever, that Buck helps him pick out.
Chris and Maddie eat pudding cups together while they recover in the hospital and then go for ice cream every week once they're out. And they all live happily ever after the end.
