Because Lotte was so small and light, Diego had absolutely no trouble carrying her back to Bellum. They got a lot of strange looks on the way there, but he ignored them. He could feel the relaxation in her body as they went, how she was less tense than before. It was a good feeling, to know that she was this relaxed now. It made him feel the slightest bit better about this shitty situation.
Finally, they reached the building, and Diego glanced at the staircase. He really didn't want to try and walk all 12 flights with Lotte in his arms, especially after the walk there. He might fall, or drop her. So he went to the elevator and pushed the twelfth floor's button, patting Lotte very lightly on the shoulder as the doors closed.