Seregrian. Hartagil

Upon hearing the news that her husband and son were due to return home at last, Seregrían sits with Hartagil, Teahesto and Bainiel to plan the homecoming

Seregrían and Hartagil argue late into the night, airing their grievances before coming to blows...

(From the chapter, "Speech in the Night")

The two orphaned Elf-maids, Seregrían and Hartagil, in the peaceful years on the Isle of Balar before the end of the First Age.

From the tale, "Red Maid, Black Blade"

Having just arrived in Herne, Seregrían makes arrangements with the innkeeper for lodgings for the Expedition

The Expedition of Bar-en-Acharn proceeds south along the road from Sarn Ford to Herne in Cardolan

Expedition:  Swanfleet rides through the rough terrain of the Yondershire

Now safe in Lindon, Hartagil breaks the news to Seregrían that she is departing to find her lost sister, Thelyndis - and Seregrían fears she is losing her sister in turn...

From the tale, "The Bond of Family"

In the midst of a bitter parting that will last for centuries, Hartagil and Seregrían tearfully recite the Gwethnoss, the Bond of Family, declaring themselves to be "sisters in all but blood"...

From the tale, "The Bond of Family"