". . . see that ye love one another with a pure heart fervently." 1 Peter 1:22b
Two of the characters displayed unselfish love. The kind of love that wants what's best for the loved regardless of the cost. And in both cases, the selfless act centered around a letter. . .
Jean Valjean, of course, showed that love when he intercepted and acted upon a letter from Marius addressed to Cosette, pledging his undying love for her. Valjean struggled with his decision:
"She was never mine to keep
She is youthful, she is free
Love is the garden of the young
Let it be
Let it be
A heart full of love
This I give you this day"
But he finally realized that Cosette needed a husband to love and care for her. Jean had raised her. Now it was time to give her wings. Jean Valjean knew he'd be lonely, but he also realized he'd be gone soon. Instead of keeping Cosette to himself, he sought Marius out and protected him during the battle, "bringing him home" safely, so he could eventually marry his daughter.
"A friend loveth at all times, and a brother is born for adversity." Proverbs 17:17
Did you notice that whenever Eponine sings, it's raining? I see that as a symbol of an unfortunate life. But, that life/trouble was washed away with the rain, as Eponine laid dying in Marius's arms. It was all worthwhile.
Eponine loved Marius, even tho' that love was not returned. Again, intercepting a letter from Cosette to Marius, Eponine decided to reveal it just before she died. Instead of feeling jealous, Eponine unselfishly gave Marius hope for the future. Not only that, but she had just shielded Marius from a bullet which ended up taking her life.