Heartwarming: Europa Universalis

  • Anytime you ally with a country that you won a war against. It takes a few years and a lot of money, trade, and royal marriages, but eventually that same country can become your best friend.
    • Especially if you do it with England and France, or Castille and Portugal.
  • Peacefully integrating another country via royal marriage and then personal union. Sure you could conquer them with your armies, but sometimes love and charm are more effective than sword and cannon.
  • By that same token, as a colonizer you can sometimes go out of your way to treat the natives well - for instance, sending doctors to help treat the diseases your settlers brought with them.
  • Starting as an oppressive nation (e.g. Muscovy or Castille) and turning them into a free, forward-thinking state, even if you have to drag them there kicking and screaming.