In FGO, there are certain servants who are connected to each other:

E.g. Queen Medb to Cu Alter, Bryn to Sigurd, Edison to Tesla, Kama to Kiara etc.

Which ones do you have and which ones are you still aiming for?

For me, I'm still looking to a Kiara rate-up sometime soon - or next year if we don't get a "surprise one". I must have both sides of the Beast and after playing Ooku, I can't see Kiara and Kama separate from each other >_>

There's also Castoria and Morgan. I already have Castoria but it would feel more fitting to also have Morgan given their connection.