Support Conversations
While building support in battle and at the castle is important, it’s even more important to advance support ranks via the support conversations. This menu can be accessed while at the castle or before a battle while selecting units. The support tab will have a list of every character, and when you click on that character it will bring up another list of every unit that one can build a support relationship with.
When units are ready to advance to the next support rank an exclamation point will appear next to their name. You just need to go in and press which units have available support conversations, watch the dialogue that happens between the two characters, and then they will advance to the next rank. Afterwards you’ll need to do any combination of battling alongside them, talking to them in the castle, or inviting them to your quarters to get the chance for another support conversation.