Kael
Deity
Varn does have at least one Brother. His elder brother Haerlond was king of the Elves in the Shadowed Vale.
I was pretty sure that the heartstone was actually stolen by their father (whose name I forget, but I think it also starts with an H. Maybe Kael never actually said and I was confusing him with his son), who lead the rebellion against Latoth but stayed behind to hold off the forces of Laroth so the others could escape. I can't actually find where it specifically says who personally stole the heartstone though, so I guess I'll accept Varn's Brother as being close enough. Haerlond is probably the one who actually took it out of the netherworld anyway, even if is father took it from Laroth.
I dont think I ever said, Arak the Erkling is Varn and Haerlonds father and he is said to be still inside the portal between the netherworld and the shadow rift, keeping Laroth at bay.
The erkling title comes from the dark germanic elven creature, it has no relation to the Harry Potter creature (except the author probably used the same source, i wrote this well before harry potter came out). If anyone thinks its werid that Varn's father was named after an evil elven creature its important to remember that Varn isnt typical of the elves of the shadow rift who are much more svartalfar in nature.
Conflicting with the Arak defender story is the fact that Rathus entered the gate to the netherworld and didn't have any real difficulties or encounter Arak.