Oscar Koch's Links
Even though they're not super close, Oscar does consider Avis to almost be a second dad to him. Almost though, its a little difficult to accept someone as your other father after losing your own not that long ago. Especially regarding how close Oscar was to his parents. His extremely introverted nature prevents him from really interacting with Avis but he does enjoy the occasional times where he sings along to his violin playing
These two are honestly the most distant of the group. Avis still cares about Oscar and considers him part of his new family. However Oscar's grumpy nature tends to cause Avis to leave him be in fear of upsetting him more. The others have it handled better anyhow.