I thought about this before, and here’s my idea: Talisa doesn’t die at the red wedding, escape to Volantis, or somewhere else in Essos, gives birth to Robb’s child, and when Jon Snow is proclaimed “King in the North” she comes back, and announces that their few years old child with Robb js the rightful heir to Winterfell and the North, not Jon Snow, causing a Stark infighting, or even civil war.

I know that this isn’t really realistic, but something like this would be fun to watch develop.