How would the 104th kids react to their S/O writing and then singing a song for them?
Eren: Absolutely overjoyed. He’ll ask them to sing it to him again after the first time, so he can learn it better, and then he might ask them to sing it if he’s ever feeling scared or sad. You can probably find him humming it to himself throughout the day cause this is their song and means so much to him.
Mikasa: Listens attentively the first time, and then hugs them cause “This is the sweetest thing anyone has ever done for me.” She’ll analyze the lyrics to it and just melt a little bit with every line. She listens to it on repeat for two weeks, and then listens to it whenever she needs a pick-me-up or is missing her S/O.
Armin: Is smiling so hard, and trying really, really hard not to. But he just can’t help it! His S/O wrote him a song, and that’s the most amazing thing ever. He’ll bring it up forever, how his S/O wrote him a song and that’s the coolest thing to happen to him ever in his entire life.