Who Am I?

[Eorl of Rohan]

I tainted their white pride with red
but stood aside while the red turned to black

I'd have betrayed if not betrayed
My yet another betrayal was with faith repaid

Sought the end but was paid in loss
Yet none shall claim in gratitude I was lacking

My high hopes welded the children
adopted and born and the beloved youngest

In the darkness resigned plunged I,
My high delight set ablaze to grief and despair