IKR?
"I've red on my ledger. I'd like to wipe it out." -- "Love is for children. I owe him a debt."
I saw somewhere in tumblr saying that they could never repay their debts for each other because how can you add one to infinity every time?
They didn't just save each other once and for all. They keep saving each other, pulling them back from the edges and fixing each other along the way. Their red is going to keep accumulating and there's no way they are able to repay all of it.