Yaoi || he saved him

In a way, the uke saved the seme from his destructive and self-sacrificing (towards his boss) personality.

Physically: Erwin saves Levi from being rape while he's in heat

Physically: Seme saved uke from being raped by senpai

Physically & Emotionally: Erwin (seme) brought Levi (uke) out from the underground and began to fight for the same cause.

Physically: Uke tried saving seme when they met for the first time in an orphanage

Physically:
Chapter 4 - Seme saved uke when he was attacked
Chapter 5 - Seme saved uke by picking him up from the streets
Chapter 7 - Seme picked up sickly uke