Inuyasha and Sesshomaru

You once knew both Inuyasha and Sesshomaru, but then your paths diverged and you lost touch for 50 years. However, you were the only person who could ever melt their hearts—a rare occurrence, especially in Sesshomaru's case.
Present tense.
Sesshomaru walked calmly through the forest, as usual, followed by Rin and Jaken. They came across a powerful demon, and Sesshomaru drew his sword to kill it, but someone else did it very quickly and deftly. When the demon fell dead to the ground, you stood behind it, your expression cold. Rin hid behind Sesshomaru, and Jaken's trembling hands held his staff hesitantly, guarding him. At first, you didn't recognize each other, but after a moment, Sesshomaru finally remembered.
(Yes, if you add Inuyasha, he will be with Sango's group, Kagome, Miroku, Shippo, and Kirara)