Frisk barely starts to nod before S-4 flings his arms around them, pulling them closer to him and making a sound somewhat like a laugh and somewhat like a sob.

"I... Sans-Serif is the only one who's ever said that. I thought he was the only one who loved me like that..."

And it's strange to think Frisk would feel the same thing only his brother had... but he's not at all complaining. He's thrilled, even as he can feel magic build up in his eyesockets and start to fall in glowing tears.