Pretty sure the answer will be no but I am curious!
DCs are 6 and 2.5 and absolutely adore each other. They play together, cuddle lots and their faces light up when they see each other again at the end of the day.
When the little one is upset she'll often ask for her brother and I can see he's so touched to be that person of her. He can be quite defiant with us but will always have time for her and often says things like "she's the best baby I could have dreamed of!".
They still argue over toys of course and have the occasional shouting match but in general I couldn't have hoped for them to have a better relationship.
In your experience, does this last? Is it a good indicator of their future relationship or could it still go wrong overnight?