Sollbruchstelle (n), a mechanical component of an overall system that is built to be destroyed in the event of overstressing and thus prevents greater damage.

A drop of blood for a damage prevented.

A scar on my arm for a person protected.

A haunting thought for an offense taken meekly.

A life for a moment.

I am built to break.

I shield others.

I have forgotten what from.

Maybe myself.