This scene takes place the same time, during the last part of the story. Where Chrom and run away from the tremors and when Lissa's attacked and received help from Lucina

Robin

"Huh?" I woke up looking around, Chrom and Lissa weren't around to be seen. Looking back I can still hear Frederick snoring. I went up and decided to wake him up.

"Frederick, psst! Frederick!" While whispering to wake him up. The armored knight soon then sits up straight while rubbing his sleepy eyes.

Frederick

Robin woke me up in the middle of the night. Damm this girl is starting to annoy me, it's not even dawn yet and I'm still hungry as I didn't want to eat that disgusting bear meat. "Frederick, have you seen Chrom or Lissa anywhere?" Robin asks, my eyes widened and look around. I couldn't see where my milord and princess is at. It couldn't be... That Robin had something to do with this?

"Robin if I found out that you killed milord, Chrom and Lissa, I will personally execute you right here, right now!" She looked at me terrified as I grabbed my silver lance and pointed it towards her throat. "Frederick! I swear I hadn't done anything to Chrom or Lissa, besides IF I did kill them, you wouldn't be awake right now." Robin was right, I was just being cautious. Now I feel bad this.

"I'm sorry Robin I—" Then the entire ground was shaking. "Woah! What happening?" Suddenly from a distance fireballs we're flying and then falling into the ground. "Frederick look! Footsteps, it must belong to Chrom and Lissa." I went to carry Robin and mounted her into my armored horse," C'mon Robin it's faster if we moved together." I then felt her arms wrap around me as we began to look for Chrom and Lissa.

It took a few minutes until we found them. I dismounted my horse and helped Robin down, since she was small petite girl. "Milord! Milady! Are you hurt?" I asked them, I can see a masked man besides them.