[he closes the door after Eren comes in, to give them some privacy. His own thoughts were so occupied with how this talk would go, he doesn't notice Eren looking around his room until he speaks up]

Hm? [He looks, seeing that Eren is looking at the violin] - Oh, yeah!

[He can't help it, his tone brightens automatically, talking about his violin]

I got lucky and found it in a secondhand store. It's a big relief.

[he clasps his hands together] I promised to play you a song, didn't I? Remind me to do that later.